Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with
knowledge
Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...
. Epistemology is considered a major subfield of philosophy, along with other major subfields such as
ethics
Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns m ...
,
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
, and
metaphysics
Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
.
Epistemologists study the nature, origin, and scope of knowledge,
epistemic justification
Justification (also called epistemic justification) is the property of belief that qualifies it as knowledge rather than mere opinion. Epistemology is the study of reasons that someone holds a rationally admissible belief (although the term is a ...
, the
rationality
Rationality is the quality of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abil ...
of
belief
A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to take i ...
, and various related issues.
Debates in epistemology are generally clustered around four core areas:
# The
philosophical analysis
Philosophical analysis is any of various techniques, typically used by philosophers in the analytic tradition, in order to "break down" (i.e. analyze) philosophical issues. Arguably the most prominent of these techniques is the analysis of concept ...
of the nature of knowledge and the conditions required for a belief to constitute knowledge, such as
truth
Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs ...
and justification
# Potential sources of knowledge and justified belief, such as
perception
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...
,
reason
Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
, and
testimony
In law and in religion, testimony is a solemn attestation as to the truth of a matter.
Etymology
The words "testimony" and "testify" both derive from the Latin word ''testis'', referring to the notion of a disinterested third-party witness.
La ...
# The structure of a body of knowledge or justified belief, including whether all justified beliefs must be derived from justified foundational beliefs or whether justification requires only a coherent set of beliefs
#
Philosophical skepticism
Philosophical skepticism ( UK spelling: scepticism; from Greek σκέψις ''skepsis'', "inquiry") is a family of philosophical views that question the possibility of knowledge. It differs from other forms of skepticism in that it even reject ...
, which questions the possibility of knowledge, and related problems, such as whether skepticism poses a threat to our ordinary knowledge claims and whether it is possible to refute skeptical arguments
In these debates and others, epistemology aims to answer questions such as "What do we know?", "What does it mean to say that we know something?", "What makes justified beliefs justified?", and "How do we know that we know?".
Background
Etymology
The word ''epistemology'' is derived from the ancient Greek ''epistēmē'', meaning "knowledge", and the suffix ''-logia'', meaning "logical
discourse
Discourse is a generalization of the notion of a conversation to any form of communication. Discourse is a major topic in social theory, with work spanning fields such as sociology, anthropology, continental philosophy, and discourse analysis. ...
" (derived from the Greek word ''logos'' meaning "discourse"). The word's appearance in English was predated by the German term ''Wissenschaftslehre'' (literally, theory of science), which was introduced by philosophers
Johann Fichte
Johann Gottlieb Fichte (; ; 19 May 1762 – 29 January 1814) was a German philosopher who became a founding figure of the philosophical movement known as German idealism, which developed from the theoretical and ethical writings of Immanuel Kan ...
and
Bernard Bolzano
Bernard Bolzano (, ; ; ; born Bernardus Placidus Johann Gonzal Nepomuk Bolzano; 5 October 1781 – 18 December 1848) was a Bohemian mathematician, logician, philosopher, theologian and Catholic priest of Italian extraction, also known for his liber ...
in the late 18th century. The word "epistemology" first appeared in 1847, in a review in New York's ''Eclectic Magazine''. It was first used as a translation of the word ''Wissenschaftslehre'' as it appears in a philosophical novel by German author
Jean Paul
Jean Paul (; born Johann Paul Friedrich Richter, 21 March 1763 – 14 November 1825) was a German Romantic writer, best known for his humorous novels and stories.
Life and work
Jean Paul was born at Wunsiedel, in the Fichtelgebirge mountain ...
:
The word "epistemology" was properly introduced into Anglophone philosophical literature by Scottish philosopher
James Frederick Ferrier
James Frederick Ferrier (16 June 1808 – 11 June 1864) was a Scottish metaphysical writer and philosopher. He introduced the word ''epistemology'' in philosophical English, as well as coining agnoiology for the study of ignorance.
Education ...
in 1854, who used it in his ''Institutes of Metaphysics'':
It is important to note that the French term ''épistémologie'' is used with a different and far narrower meaning than the English term "epistemology", being used by French philosophers to refer solely to
philosophy of science
Philosophy of science is a branch of philosophy concerned with the foundations, methods, and implications of science. The central questions of this study concern what qualifies as science, the reliability of scientific theories, and the ultim ...
. For instance,
Émile Meyerson
Émile Meyerson (; 12 February 1859 – 2 December 1933) was a Polish-born French epistemologist, chemist, and philosopher of science. Meyerson was born in Lublin, Poland. He died in his sleep of a heart attack at the age of 74.
Biography
Meyerso ...
opened his ''Identity and Reality'', written in 1908, with the remark that the word 'is becoming current' as equivalent to 'the philosophy of the sciences.'
History of epistemology
Epistemology, as a distinct field of inquiry, predates the introduction of the term into the lexicon of philosophy.
John Locke
John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenment, Enlightenment thinkers and commonly known as the "father of liberalism ...
, for instance, described his efforts in ''
Essay Concerning Human Understanding
''An Essay Concerning Human Understanding'' is a work by John Locke concerning the foundation of human knowledge and understanding. It first appeared in 1689 (although dated 1690) with the printed title ''An Essay Concerning Humane Understand ...
'' (1689) as an inquiry "into the original, certainty, and extent of human knowledge, together with the grounds and degrees of belief, opinion, and assent".
Almost every major historical philosopher has considered questions about what we know and how we know it. Among the
Ancient Greek philosophers
Ancient Greek philosophy arose in the 6th century BC, marking the end of the Greek Dark Ages. Greek philosophy continued throughout the Hellenistic period and the period in which Greece and most Greek-inhabited lands were part of the Roman Empire ...
,
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
distinguished between inquiry regarding what we know and inquiry regarding what exists, particularly in the ''
Republic
A republic () is a "state in which power rests with the people or their representatives; specifically a state without a monarchy" and also a "government, or system of government, of such a state." Previously, especially in the 17th and 18th c ...
'', the ''
Theaetetus Theaetetus (Θεαίτητος) is a Greek name which could refer to:
* Theaetetus (mathematician) (c. 417 BC – 369 BC), Greek geometer
* ''Theaetetus'' (dialogue), a dialogue by Plato, named after the geometer
* Theaetetus (crater), a lunar imp ...
'', and the ''
Meno
''Meno'' (; grc-gre, Μένων, ''Ménōn'') is a Socratic dialogue by Plato. Meno begins the dialogue by asking Socrates whether virtue is taught, acquired by practice, or comes by nature. In order to determine whether virtue is teachable ...
''. A number of important epistemological concerns also appeared in the works of
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
.
During the subsequent
Hellenistic period
In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in 3 ...
, philosophical schools began to appear which had a greater focus on epistemological questions, often in the form of
philosophical skepticism
Philosophical skepticism ( UK spelling: scepticism; from Greek σκέψις ''skepsis'', "inquiry") is a family of philosophical views that question the possibility of knowledge. It differs from other forms of skepticism in that it even reject ...
. For instance, the
Pyrrhonian skepticism
Pyrrhonism is a school of philosophical skepticism founded by Pyrrho in the fourth century BCE. It is best known through the surviving works of Sextus Empiricus, writing in the late second century or early third century CE.
History
Pyrrho of E ...
of
Pyrrho
Pyrrho of Elis (; grc, Πύρρων ὁ Ἠλεῖος, Pyrrhо̄n ho Ēleios; ), born in Elis, Greece, was a Greek philosopher of Classical antiquity, credited as being the first Greek skeptic philosopher and founder of Pyrrhonism.
Life
...
and
Sextus Empiricus
Sextus Empiricus ( grc-gre, Σέξτος Ἐμπειρικός, ; ) was a Ancient Greece, Greek Pyrrhonism, Pyrrhonist philosopher and Empiric school physician. His philosophical works are the most complete surviving account of ancient Greek and ...
held that
eudaimonia
Eudaimonia (Greek: εὐδαιμονία ; sometimes anglicized as eudaemonia or eudemonia, ) is a Greek word literally translating to the state or condition of 'good spirit', and which is commonly translated as 'happiness' or 'welfare'.
In wor ...
(flourishing, happiness, or "the good life") could be attained through the application of
epoché
Epoché ( ἐποχή ''epokhē'', "cessation") is an ancient Greek term. In Hellenistic philosophy it is a technical term typically translated as " suspension of judgment" but also as "withholding of assent". In the modern philosophy of Phenomen ...
(suspension of judgment) regarding all non-evident matters. Pyrrhonism was particularly concerned with undermining the epistemological
dogma
Dogma is a belief or set of beliefs that is accepted by the members of a group without being questioned or doubted. It may be in the form of an official system of principles or doctrines of a religion, such as Roman Catholicism, Judaism, Islam ...
s of
Stoicism
Stoicism is a school of Hellenistic philosophy founded by Zeno of Citium in Athens in the early 3rd century Common Era, BCE. It is a philosophy of personal virtue ethics informed by its system of logic and its views on the natural world, asser ...
and
Epicureanism
Epicureanism is a system of philosophy founded around 307 BC based upon the teachings of the ancient Greek philosopher Epicurus. Epicureanism was originally a challenge to Platonism. Later its main opponent became Stoicism.
Few writings by Epi ...
. The other major school of Hellenistic skepticism was
Academic skepticism
Academic skepticism refers to the skeptical period of ancient Platonism dating from around 266 BCE, when Arcesilaus became scholarch of the Platonic Academy, until around 90 BCE, when Antiochus of Ascalon rejected skepticism, although individua ...
, most notably defended by
Carneades
Carneades (; el, Καρνεάδης, ''Karneadēs'', "of Carnea"; 214/3–129/8 BC) was a Greek philosopher and perhaps the most prominent head of the Skeptical Academy in ancient Greece. He was born in Cyrene. By the year 159 BC, he had begu ...
and
Arcesilaus
Arcesilaus (; grc-gre, Ἀρκεσίλαος; 316/5–241/0 BC) was a Greek Hellenistic philosopher. He was the founder of Academic Skepticism and what is variously called the Second or Middle or New Academy – the phase of the Platonic Acade ...
, which predominated in the
Platonic Academy
The Academy (Ancient Greek: Ἀκαδημία) was founded by Plato in c. 387 BC in Classical Athens, Athens. Aristotle studied there for twenty years (367–347 BC) before founding his own school, the Lyceum (classical), Lyceum. The Academy ...
for almost two centuries.
In ancient India the
Ajñana
''Ajñāna'' () was one of the ''nāstika'' or "heterodox" schools of ancient Indian philosophy, and the ancient school of radical Indian skepticism. It was a Śramaṇa movement and a major rival of early Buddhism, Jainism and the Ājīvika ...
school of
ancient Indian philosophy
This page lists some links to ancient philosophy, namely philosophical thought extending as far as early post-classical history ().
Overview
Genuine philosophical thought, depending upon original individual insights, arose in many cultures ...
promoted skepticism. Ajñana was a Śramaṇa movement and a major rival of
early Buddhism The term Early Buddhism can refer to at least two distinct periods in the History of Buddhism, mostly in the History of Buddhism in India:
* Pre-sectarian Buddhism, which refers to the teachings and monastic organization and structure, founded by Ga ...
,
Jainism
Jainism ( ), also known as Jain Dharma, is an Indian religions, Indian religion. Jainism traces its spiritual ideas and history through the succession of twenty-four tirthankaras (supreme preachers of ''Dharma''), with the first in the current ...
and the
Ājīvika
''Ajivika'' (IAST: ) is one of the ''nāstika'' or "heterodox" schools of Indian philosophy.Natalia Isaeva (1993), Shankara and Indian Philosophy, State University of New York Press, , pages 20-23James Lochtefeld, "Ajivika", ''The Illustrated ...
school. They held that it was impossible to obtain knowledge of metaphysical nature or ascertain the truth value of philosophical propositions; and even if knowledge was possible, it was useless and disadvantageous for final salvation. They were specialized in refutation without propagating any positive doctrine of their own.
After the ancient philosophical era but before the modern philosophical era, a number of Medieval philosophers also engaged with epistemological questions at length. Most notable among the Medievals for their contributions to epistemology were
Thomas Aquinas
Thomas Aquinas, OP (; it, Tommaso d'Aquino, lit=Thomas of Aquino; 1225 – 7 March 1274) was an Italian Dominican friar and priest who was an influential philosopher, theologian and jurist in the tradition of scholasticism; he is known wi ...
,
John Duns Scotus
John Duns Scotus ( – 8 November 1308), commonly called Duns Scotus ( ; ; "Duns the Scot"), was a Scottish Catholic priest and Franciscan friar, university professor, philosopher, and theologian. He is one of the four most important ...
, and
William of Ockham
William of Ockham, OFM (; also Occam, from la, Gulielmus Occamus; 1287 – 10 April 1347) was an English Franciscan friar, scholastic philosopher, apologist, and Catholic theologian, who is believed to have been born in Ockham, a small vill ...
.
In the Islamic epistemology
Islamic Golden Age
The Islamic Golden Age was a period of cultural, economic, and scientific flourishing in the history of Islam, traditionally dated from the 8th century to the 14th century. This period is traditionally understood to have begun during the reign ...
which was booming prior to the Age of Enlightenment in Europe. One of the most prominent and influential philosophers, theologians, jurists, logicians and mystics Abu Hamid
Al-Ghazali
Al-Ghazali ( – 19 December 1111; ), full name (), and known in Persian-speaking countries as Imam Muhammad-i Ghazali (Persian: امام محمد غزالی) or in Medieval Europe by the Latinized as Algazelus or Algazel, was a Persian polymat ...
wrote over 70 books, including his best-known work in 1107 CE, his spiritual autobiography, "Deliverance from Error" (Al-Munqidh min al-Dalal). In this book Al-Ghazali was seeking to know what we can be certain about: what is true knowledge and not just opinion? To accomplish this goal, he would first consider what kinds of things we can know. This involves a study of epistemology, the theory of knowledge.
Epistemology largely came to the fore in philosophy during the early modern period, which historians of philosophy traditionally divide up into a dispute between
empiricists
In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empiri ...
(including
Francis Bacon
Francis Bacon, 1st Viscount St Alban (; 22 January 1561 – 9 April 1626), also known as Lord Verulam, was an English philosopher and statesman who served as Attorney General and Lord Chancellor of England. Bacon led the advancement of both ...
,
John Locke
John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenment, Enlightenment thinkers and commonly known as the "father of liberalism ...
,
David Hume
David Hume (; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) Cranston, Maurice, and Thomas Edmund Jessop. 2020 999br>David Hume" ''Encyclopædia Britannica''. Retrieved 18 May 2020. was a Scottish Enlightenment philo ...
, and
George Berkeley
George Berkeley (; 12 March 168514 January 1753) – known as Bishop Berkeley (Bishop of Cloyne of the Anglican Church of Ireland) – was an Anglo-Irish philosopher whose primary achievement was the advancement of a theory he called "immate ...
) and
rationalists
In philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification".Lacey, A.R. (1996), ''A Dictionary of Philosophy ...
(including
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathem ...
,
Baruch Spinoza
Baruch (de) Spinoza (born Bento de Espinosa; later as an author and a correspondent ''Benedictus de Spinoza'', anglicized to ''Benedict de Spinoza''; 24 November 1632 – 21 February 1677) was a Dutch philosopher of Portuguese-Jewish origin, b ...
, and
Gottfried Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mathem ...
). The debate between them has often been framed using the question of whether knowledge comes primarily from
sensory experience
The theory of sense data is a view in the philosophy of perception, popularly held in the early 20th century by philosophers such as Bertrand Russell, C. D. Broad, H. H. Price, A. J. Ayer, and G. E. Moore. Sense data are taken to be mind-depende ...
(empiricism), or whether a significant portion of our knowledge is derived entirely from our faculty of
reason
Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
(rationalism). According to some scholars, this dispute was resolved in the late 18th century by
Immanuel Kant
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and ...
, whose
transcendental idealism
Transcendental idealism is a philosophical system founded by German philosopher Immanuel Kant in the 18th century. Kant's epistemological program is found throughout his '' Critique of Pure Reason'' (1781). By ''transcendental'' (a term that des ...
famously made room for the view that "though all our knowledge begins with experience, it by no means follows that all nowledgearises out of experience".
Contemporary historiography
There are a number of different methods that contemporary scholars use when trying to understand the relationship between past epistemology and contemporary epistemology. One of the most contentious questions is this: "Should we assume that the problems of epistemology are perennial, and that trying to reconstruct and evaluate Plato's or Hume's or Kant's arguments is meaningful for current debates, too?" Similarly, there is also a question of whether contemporary philosophers should aim to ''rationally reconstruct and evaluate'' historical views in epistemology, or to ''merely describe'' them.
Barry Stroud
Barry Stroud (; 18 May 1935 – 9 August 2019) was a Canadian philosopher and professor at the University of California, Berkeley. Known especially for his work on philosophical skepticism, he wrote about David Hume, Ludwig Wittgenstein, the metap ...
claims that doing epistemology competently requires the historical study of past attempts to find philosophical understanding of the nature and scope of human knowledge. He argues that since inquiry may progress over time, we may not realize how different the questions that contemporary epistemologists ask are from questions asked at various different points in the history of philosophy.
Central concepts in epistemology
Knowledge
Nearly all debates in epistemology are in some way related to
knowledge
Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...
. Most generally, "knowledge" is a familiarity, awareness, or understanding of someone or something, which might include facts (
propositional knowledge
In epistemology, descriptive knowledge (also known as propositional knowledge, knowing-that, declarative knowledge, or constative knowledge) is knowledge that can be expressed in a declarative sentence or an indicative proposition. "Knowing-that" c ...
), skills (
procedural knowledge
Procedural knowledge (also known as Know-how, knowing-how, and sometimes referred to as practical knowledge, imperative knowledge, or performative knowledge) is the knowledge exercised in the performance of some task. Unlike descriptive knowledge ( ...
), or objects ( acquaintance knowledge). Philosophers tend to draw an important distinction between three different senses of "knowing" something: " knowing that" (knowing the truth of propositions), " knowing how" (understanding how to perform certain actions), and " knowing by acquaintance" (directly perceiving an object, being familiar with it, or otherwise coming into contact with it). Epistemology is primarily concerned with the first of these forms of knowledge, propositional knowledge. All three senses of "knowing" can be seen in our ordinary use of the word. In mathematics, you can know 2 + 2 = 4, but there is also knowing to add two numbers, and knowing a (e.g., knowing other persons, or knowing oneself), (e.g., one's hometown), (e.g., cars), or (e.g., addition). While these distinctions are not explicit in English, they are explicitly made in other languages, including French, Portuguese, Spanish, Romanian, German and Dutch (although some languages closely related to English have been said to retain these verbs, such as Scots). The theoretical interpretation and significance of these linguistic issues remains controversial.
In his paper ''On Denoting'' and his later book ''Problems of Philosophy'',
Bertrand Russell
Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, ...
brought a great deal of attention to the distinction between "
knowledge by description
In philosophy, a distinction is often made between two different kinds of knowledge: knowledge by acquaintance and knowledge by description. Whereas knowledge by description is something like ordinary propositional knowledge (e.g. "I know that ...
" and "
knowledge by acquaintance
In philosophy, a distinction is often made between two different kinds of knowledge: knowledge by acquaintance and knowledge by description. Whereas knowledge by description is something like ordinary propositional knowledge (e.g. "I know that ...
".
Gilbert Ryle
Gilbert Ryle (19 August 1900 – 6 October 1976) was a British philosopher, principally known for his critique of Cartesian dualism, for which he coined the phrase "ghost in the machine." He was a representative of the generation of British ord ...
is similarly credited with bringing more attention to the distinction between knowing how and knowing that in ''
The Concept of Mind
''The Concept of Mind'' is a 1949 book by philosopher Gilbert Ryle, in which the author argues that "mind" is "a philosophical illusion hailing chiefly from René Descartes and sustained by logical errors and 'category mistakes' which have becom ...
''. In ''Personal Knowledge'',
Michael Polanyi
Michael Polanyi (; hu, Polányi Mihály; 11 March 1891 – 22 February 1976) was a Hungarian-British polymath, who made important theoretical contributions to physical chemistry, economics, and philosophy. He argued that positivism supplies ...
argues for the epistemological relevance of knowledge how and knowledge that; using the example of the act of balance involved in riding a bicycle, he suggests that the theoretical knowledge of the physics involved in maintaining a state of balance cannot substitute for the practical knowledge of how to ride, and that it is important to understand how both are established and grounded. This position is essentially Ryle's, who argued that a failure to acknowledge the distinction between "knowledge that" and "knowledge how" leads to
infinite regress
An infinite regress is an infinite series of entities governed by a recursive principle that determines how each entity in the series depends on or is produced by its predecessor. In the epistemic regress, for example, a belief is justified beca ...
.
''A priori'' and ''a posteriori'' knowledge
One of the most important distinctions in epistemology is between what can be known ''a priori'' (independently of experience) and what can be known ''a posteriori'' (through experience). The terms originate from the Analytic methods of Aristotle's
Organon
The ''Organon'' ( grc, Ὄργανον, meaning "instrument, tool, organ") is the standard collection of Aristotle's six works on logical analysis and dialectic. The name ''Organon'' was given by Aristotle's followers, the Peripatetics.
The si ...
, and may be roughly defined as follows:
* ''
A priori
("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...
'' knowledge is knowledge that is known independently of experience (that is, it is non-empirical, or arrived at before experience, usually by reason). It will henceforth be acquired through anything that is independent from experience.
* ''
A posteriori
("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...
'' knowledge is knowledge that is known by experience (that is, it is empirical, or arrived at through experience).
Views that emphasize the importance of ''a priori'' knowledge are generally classified as rationalist. Views that emphasize the importance of ''a posteriori'' knowledge are generally classified as
empiricist
In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...
.
Belief
One of the core concepts in epistemology is ''belief''. A belief is an attitude that a person holds regarding anything that they take to be true. For instance, to believe that snow is white is comparable to accepting the truth of the
proposition
In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
"snow is white". Beliefs can be ''occurrent'' (e.g. a person actively thinking "snow is white"), or they can be ''dispositional'' (e.g. a person who if asked about the color of snow would assert "snow is white"). While there is not universal agreement about the nature of belief, most contemporary philosophers hold the view that a disposition to express belief ''B'' qualifies as holding the belief ''B''. There are various different ways that contemporary philosophers have tried to describe beliefs, including as representations of ways that the world could be (
Jerry Fodor
Jerry Alan Fodor (; April 22, 1935 – November 29, 2017) was an American philosopher and the author of many crucial works in the fields of philosophy of mind and cognitive science. His writings in these fields laid the groundwork for the modu ...
), as dispositions to act as if certain things are true (
Roderick Chisholm
Roderick Milton Chisholm (; November 27, 1916 – January 19, 1999) was an American philosopher known for his work on epistemology, metaphysics, free will, value theory, and the philosophy of perception.
The ''Stanford Encyclopedia of Philosophy ...
), as interpretive schemes for making sense of someone's actions (
Daniel Dennett
Daniel Clement Dennett III (born March 28, 1942) is an American philosopher, writer, and cognitive scientist whose research centers on the philosophy of mind, philosophy of science, and philosophy of biology, particularly as those fields relat ...
and Donald Davidson), or as mental states that fill a particular function (
Hilary Putnam
Hilary Whitehall Putnam (; July 31, 1926 – March 13, 2016) was an American philosopher, mathematician, and computer scientist, and a major figure in analytic philosophy in the second half of the 20th century. He made significant contributions ...
). Some have also attempted to offer significant revisions to our notion of belief, including eliminativists about belief who argue that there is no phenomenon in the natural world which corresponds to our folk psychological concept of belief (
Paul Churchland
Paul Montgomery Churchland (born October 21, 1942) is a Canadian philosopher known for his studies in neurophilosophy and the philosophy of mind. After earning a Ph.D. from the University of Pittsburgh under Wilfrid Sellars (1969), Churchland ros ...
) and formal epistemologists who aim to replace our bivalent notion of belief ("either I have a belief or I don't have a belief") with the more permissive, probabilistic notion of credence ("there is an entire spectrum of degrees of belief, not a simple dichotomy between belief and non-belief").
While belief plays a significant role in epistemological debates surrounding knowledge and justification, it also has many other philosophical debates in its own right. Notable debates include: "What is the rational way to revise one's beliefs when presented with various sorts of evidence?"; "Is the content of our beliefs entirely determined by our mental states, or do the relevant facts have any bearing on our beliefs (e.g. if I believe that I'm holding a glass of water, is the non-mental fact that water is H2O part of the content of that belief)?"; "How fine-grained or coarse-grained are our beliefs?"; and "Must it be possible for a belief to be expressible in language, or are there non-linguistic beliefs?"
Truth
Truth
Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs ...
is the property or state of being in accordance with facts or reality. On most views, truth is the correspondence of language or thought to a mind-independent world. This is called the
correspondence theory of truth
In metaphysics and philosophy of language, the correspondence theory of truth states that the truth or falsity of a statement is determined only by how it relates to the world and whether it accurately describes (i.e., corresponds with) that world ...
. Among philosophers who think that it is possible to analyze the conditions necessary for knowledge, virtually all of them accept that truth is such a condition. There is much less agreement about the extent to which a knower must know ''why'' something is true in order to know. On such views, something being known implies that it is true. However, this should not be confused for the more contentious view that one must know that one knows in order to know (the KK principle).
Epistemologists disagree about whether belief is the only
truth-bearer
A truth-bearer is an entity that is said to be either true or false and nothing else. The thesis that some things are true while others are false has led to different theories about the nature of these entities. Since there is divergence of o ...
. Other common suggestions for things that can bear the property of being true include
propositions
In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
thought
In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, a ...
s,
utterance
In spoken language analysis, an utterance is a continuous piece of speech, often beginning and ending with a clear pause. In the case of oral languages, it is generally, but not always, bounded by silence. Utterances do not exist in written langu ...
s, and
judgment
Judgement (or US spelling judgment) is also known as ''adjudication'', which means the evaluation of evidence to decision-making, make a decision. Judgement is also the ability to make considered decisions. The term has at least five distinct u ...
s. Plato, in his
Gorgias
Gorgias (; grc-gre, Γοργίας; 483–375 BC) was an ancient Greek sophist, pre-Socratic philosopher, and rhetorician who was a native of Leontinoi in Sicily. Along with Protagoras, he forms the first generation of Sophists. Several doxogr ...
, argues that belief is the most commonly invoked truth-bearer.
Many of the debates regarding truth are at the crossroads of epistemology and
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
. Some contemporary debates regarding truth include: How do we define truth? Is it even possible to give an informative definition of truth? What things are truth-bearers and are therefore capable of being true or false? Are truth and falsity
bivalent Bivalent may refer to:
* Bivalent (chemistry), a molecule formed from two or more atoms bound together
*Bivalent (engine), an engine that can operate on two different types of fuel
*Bivalent (genetics), a pair of homologous chromosomes
*Bivalent log ...
, or are there other truth values? What are the
criteria of truth
In epistemology, criteria of truth (or tests of truth) are standards and rules used to judge the accuracy of statements and claims. They are tools of verification, and as in the problem of the criterion, the reliability of these tools is disputed ...
that allow us to identify it and to distinguish it from falsity? What role does truth play in constituting
knowledge
Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...
? And is truth
absolute Absolute may refer to:
Companies
* Absolute Entertainment, a video game publisher
* Absolute Radio, (formerly Virgin Radio), independent national radio station in the UK
* Absolute Software Corporation, specializes in security and data risk manage ...
, or is it merely
relative
Relative may refer to:
General use
*Kinship and family, the principle binding the most basic social units society. If two people are connected by circumstances of birth, they are said to be ''relatives''
Philosophy
*Relativism, the concept that ...
to one's perspective?
Justification
As the term "justification" is used in epistemology, a belief is justified if one has good reason for holding it. Loosely speaking, justification is the ''reason'' that someone holds a rationally admissible belief, on the assumption that it is a ''good reason'' for holding it. Sources of justification might include
perceptual experience
Experience refers to Consciousness, conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these conscious processes. Understood as a conscious event in the widest sense, ex ...
(the evidence of the senses),
reason
Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
, and authoritative
testimony
In law and in religion, testimony is a solemn attestation as to the truth of a matter.
Etymology
The words "testimony" and "testify" both derive from the Latin word ''testis'', referring to the notion of a disinterested third-party witness.
La ...
, among others. Importantly however, a belief being justified does ''not'' guarantee that the belief is true, since a person could be justified in forming beliefs based on very convincing evidence that was nonetheless deceiving.
Internalism and externalism
A central debate about the nature of justification is a debate between epistemological externalists on the one hand and epistemological internalists on the other. While epistemic externalism first arose in attempts to overcome the Gettier problem, it has flourished in the time since as an alternative way of conceiving of epistemic justification. The initial development of epistemic externalism is often attributed to
Alvin Goldman
Alvin Ira Goldman (born 1938) is an American philosopher who is Emeritus Board of Governors Professor of Philosophy and Cognitive Science at Rutgers University in New Jersey and a leading figure in epistemology.
Education and career
Goldman ea ...
, although numerous other philosophers have worked on the topic in the time since.
Externalists hold that factors deemed "external", meaning outside of the psychological states of those who gain knowledge, can be conditions of justification. For example, an externalist response to the Gettier problem is to say that for a justified true belief to count as knowledge, there must be a link or dependency between the belief and the state of the external world. Usually, this is understood to be a causal link. Such causation, to the extent that it is "outside" the mind, would count as an external, knowledge-yielding condition. Internalists, on the other hand, assert that all knowledge-yielding conditions are within the psychological states of those who gain knowledge.
Though unfamiliar with the internalist/externalist debate himself, many point to
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathem ...
as an early example of the internalist path to justification. He wrote that because the only method by which we perceive the external world is through our senses, and that, because the senses are not infallible, we should not consider our concept of knowledge infallible. The only way to find anything that could be described as "indubitably true", he advocates, would be to see things "clearly and distinctly". He argued that if there is an omnipotent, good being who made the world, then it's reasonable to believe that people are made with the ability to know. However, this does not mean that man's ability to know is perfect. God gave man the ability to know but not with omniscience. Descartes said that man must use his capacities for knowledge correctly and carefully through methodological doubt.
The dictum "Cogito ergo sum" (I think, therefore I am) is also commonly associated with Descartes's theory. In his own methodological doubt—doubting everything he previously knew so he could start from a blank slate—the first thing that he could not logically bring himself to doubt was his own existence: "I do not exist" would be a contradiction in terms. The act of saying that one does not exist assumes that someone must be making the statement in the first place. Descartes could doubt his senses, his body, and the world around him—but he could not deny his own existence, because he was able to doubt and must exist to manifest that doubt. Even if some "evil genius" were deceiving him, he would have to exist to be deceived. This one sure point provided him with what he called his Archimedean point, in order to further develop his foundation for knowledge. Simply put, Descartes's epistemological justification depended on his indubitable belief in his own existence and his clear and distinct knowledge of God.
Defining knowledge
A central issue in epistemology is the question of what the nature of knowledge is or how to define it. Sometimes the expressions "theory of knowledge" and "analysis of knowledge" are used specifically for this form of inquiry. The term "knowledge" has various meanings in
natural language
In neuropsychology, linguistics, and philosophy of language, a natural language or ordinary language is any language that has evolved naturally in humans through use and repetition without conscious planning or premeditation. Natural languages ...
. It can refer to an
awareness
Awareness is the state of being conscious of something. More specifically, it is the ability to directly know and perceive, to feel, or to be cognizant of events. Another definition describes it as a state wherein a subject is aware of some inform ...
of
fact
A fact is a datum about one or more aspects of a circumstance, which, if accepted as true and proven true, allows a logical conclusion to be reached on a true–false evaluation. Standard reference works are often used to check facts. Scient ...
s, as in knowing that
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
is a planet, to a possession of
skill
A skill is the learned ability to act with determined results with good execution often within a given amount of time, energy, or both. Skills can often be divided into domain-general and domain-specific skills. For example, in the domain of wo ...
s, as in knowing how to swim, or to an
experiential
Experience refers to conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these conscious processes. Understood as a conscious event in the widest sense, experience involv ...
acquaintance, as in knowing
Daniel Craig
Daniel Wroughton Craig (born 2 March 1968) is an English-American actor who gained international fame playing the secret agent James Bond in the film series, beginning with '' Casino Royale'' (2006) and in four further instalments, up to '' ...
personally. Factual knowledge, also referred to as ''propositional knowledge'' or ''
descriptive knowledge
In epistemology, descriptive knowledge (also known as propositional knowledge, knowing-that, declarative knowledge, or constative knowledge) is knowledge that can be expressed in a declarative sentence or an indicative proposition. "Knowing-that" c ...
'', plays a special role in epistemology. On the linguistic level, it is distinguished from the other forms of knowledge since it can be expressed through a that-clause, i.e. using a formulation like "They know that..." followed by the known
proposition
In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
.
Some features of factual knowledge are widely accepted: it is a form of cognitive success that establishes epistemic contact with
reality
Reality is the sum or aggregate of all that is real or existent within a system, as opposed to that which is only imaginary. The term is also used to refer to the ontological status of things, indicating their existence. In physical terms, r ...
. However, there are still various disagreements about its exact nature even though it has been studied intensely. Different factors are responsible for these disagreements. Some theorists try to furnish a practically useful definition by describing its most noteworthy and easily identifiable features. Others engage in an
analysis of knowledge
Definitions of knowledge try to determine the essential features of knowledge. Closely related terms are conception of knowledge, theory of knowledge, and analysis of knowledge. Some general features of knowledge are widely accepted among philoso ...
, which aims to provide a theoretically precise definition that identifies the set of essential features characteristic for all instances of knowledge and only for them. Differences in the
methodology
In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bri ...
may also cause disagreements. In this regard, some epistemologists use abstract and general intuitions in order to arrive at their definitions. A different approach is to start from concrete individual cases of knowledge to determine what all of them have in common. Yet another method is to focus on linguistic evidence by studying how the term "knowledge" is commonly used. Different standards of knowledge are further sources of disagreement. A few theorists set these standards very high by demanding that absolute certainty or infallibility is necessary. On such a view, knowledge is a very rare thing. Theorists more in tune with
ordinary language
Ordinary language philosophy (OLP) is a philosophical methodology that sees traditional philosophical problems as rooted in misunderstandings philosophers develop by distorting or forgetting how words are ordinarily used to convey meaning in ...
usually demand lower standards and see knowledge as something commonly found in everyday life.
As justified true belief
The historically most influential definition, discussed since
ancient Greek philosophy
Ancient Greek philosophy arose in the 6th century BC, marking the end of the Greek Dark Ages. Greek philosophy continued throughout the Hellenistic period and the period in which Greece and most Greek-inhabited lands were part of the Roman Empire ...
, characterizes knowledge in relation to three essential features: as (1) a
belief
A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to take i ...
that is (2)
true
True most commonly refers to truth, the state of being in congruence with fact or reality.
True may also refer to:
Places
* True, West Virginia, an unincorporated community in the United States
* True, Wisconsin, a town in the United States
* Tr ...
and (3) justified. There is still wide acceptance that the first two features are correct, i.e. that knowledge is a
mental state
A mental state, or a mental property, is a state of mind of a person. Mental states comprise a diverse class, including perception, pain experience, belief, desire, intention, emotion, and memory. There is controversy concerning the exact definiti ...
that affirms a true proposition. However, there is a lot of dispute about the third feature: justification. This feature is usually included to distinguish knowledge from true beliefs that rest on
superstition
A superstition is any belief or practice considered by non-practitioners to be irrational or supernatural, attributed to fate or magic, perceived supernatural influence, or fear of that which is unknown. It is commonly applied to beliefs and ...
,
luck
Luck is the phenomenon and belief that defines the experience of improbable events, especially improbably positive or negative ones. The naturalistic interpretation is that positive and negative events may happen at any time, both due to rand ...
y guesses, or faulty reasoning. This expresses the idea that knowledge is not the same as being right about something. Traditionally, justification is understood as the possession of evidence: a belief is justified if the believer has good evidence supporting it. Such evidence could be a
perceptual experience
Experience refers to Consciousness, conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these conscious processes. Understood as a conscious event in the widest sense, ex ...
, a
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
, or a second belief.
Gettier problem and alternative definitions
The justified-true-belief account of knowledge came under severe criticism in the second half of the 20th century, when
Edmund Gettier
Edmund Lee Gettier III (; October 31, 1927 – March 23, 2021) was an American philosopher at the University of Massachusetts Amherst. He is best known for his short 1963 article "Is Justified True Belief Knowledge?", which has generated an exten ...
proposed various counterexamples. In a famous so-called Gettier-case, a person is driving on a country road. There are many barn façades along this road and only one real barn. But it is not possible to tell the difference between them from the road. The person then stops by a fortuitous coincidence in front of the only real barn and forms the belief that it is a barn. The idea behind this thought experiment is that this is not knowledge even though the belief is both justified and true. The reason is that it is just a lucky accident since the person cannot tell the difference: they would have formed exactly the same justified belief if they had stopped at another site, in which case the belief would have been false.
Various additional examples were proposed along similar lines. Most of them involve a justified true belief that apparently fails to amount to knowledge because the belief's justification is in some sense not relevant to its truth. These counterexamples have provoked very diverse responses. Some theorists think that one only needs to modify one's conception of justification to avoid them. But the more common approach is to search for an additional criterion. On this view, all cases of knowledge involve a justified true belief but some justified true beliefs do not amount to knowledge since they lack this additional feature. There are diverse suggestions for this fourth criterion. Some epistemologists require that no false belief is involved in the justification or that no
defeater
A defeater of a belief is evidence that this belief is false. Defeaters are of particular interest to epistemology since they affect whether a belief is justified. An important distinction is between undercutting and rebutting defeaters. Undercu ...
of the belief is present. A different approach is to require that the belief tracks truth, i.e. that the person would not have the belief if it was false. Some even require that the justification has to be infallible, i.e. that it necessitates the belief's truth.
A quite different approach is to affirm that the justified-true-belief account of knowledge is deeply flawed and to seek a complete reconceptualization of knowledge. These reconceptualizations often do not require justification at all. One such approach is to require that the true belief was produced by a reliable process. Naturalized epistemologists often hold that the believed fact has to cause the belief.Virtue theorists are also interested in how the belief is produced. For them, the belief must be a manifestation of a cognitive virtue.
The value problem
We generally assume that knowledge is more valuable than mere true belief. If so, what is the explanation? A formulation of the value problem in epistemology first occurs in
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
's
Meno
''Meno'' (; grc-gre, Μένων, ''Ménōn'') is a Socratic dialogue by Plato. Meno begins the dialogue by asking Socrates whether virtue is taught, acquired by practice, or comes by nature. In order to determine whether virtue is teachable ...
. Socrates points out to Meno that a man who knew the way to Larissa could lead others there correctly. But so, too, could a man who had true beliefs about how to get there, even if he had not gone there or had any knowledge of Larissa. Socrates says that it seems that both knowledge and true opinion can guide action. Meno then wonders why knowledge is valued more than true belief and why knowledge and true belief are different. Socrates responds that knowledge is more valuable than mere true belief because it is tethered or justified. Justification, or working out the reason for a true belief, locks down true belief.
The problem is to identify what (if anything) makes knowledge more valuable than mere true belief, or that makes knowledge more valuable than a mere minimal conjunction of its components, such as justification, safety, sensitivity, statistical likelihood, and anti-Gettier conditions, on a particular analysis of knowledge that conceives of knowledge as divided into components (to which knowledge-first epistemological theories, which posit knowledge as fundamental, are notable exceptions). The value problem re-emerged in the philosophical literature on epistemology in the twenty-first century following the rise of
virtue epistemology
Virtue epistemology is a contemporary philosophical approach to epistemology that stresses the importance of intellectual and specifically epistemic virtues. A distinguishing factor of virtue theories is that they use for the evaluation of knowled ...
in the 1980s, partly because of the obvious link to the concept of value in ethics.
Virtue epistemology
In contemporary philosophy, epistemologists including
Ernest Sosa
Ernest Sosa (born June 17, 1940) is an American philosopher primarily interested in epistemology. Since 2007 he has been Board of Governors Professor of Philosophy at Rutgers University, but he spent most of his career at Brown University.
Educa ...
,
John Greco
John Patrick Greco, Jr. (born March 24, 1985) is a former American football guard. He was drafted by the St. Louis Rams in the third round of the 2008 NFL Draft. He played college football at the University of Toledo.
Early years
Greco was n ...
,
Jonathan Kvanvig
Jonathan Lee Kvanvig (born December 7, 1954) is Professor of Philosophy at Washington University in St. Louis.
Kvanvig has published extensively in areas such as epistemology, philosophy of religion, logic, and philosophy of language. Some of his ...
,
Linda Zagzebski
Linda Trinkaus Zagzebski (born 1946) is an American philosopher. She is the Emerita George Lynn Cross Research Professor, as well as Emerita Kingfisher College Chair of the Philosophy of Religion and Ethics, at the University of Oklahoma. She wr ...
, and
Duncan Pritchard
Duncan Pritchard is the chancellor's professor of philosophy and the director of graduate studies at the University of California, Irvine. He was previously professor of philosophy and chair in epistemology at the University of Edinburgh. His res ...
have defended virtue epistemology as a solution to the value problem. They argue that epistemology should also evaluate the "properties" of people as epistemic agents (i.e. intellectual virtues), rather than merely the properties of propositions and propositional mental attitudes.
The value problem has been presented as an argument against epistemic
reliabilism Reliabilism, a category of theories in the philosophical discipline of epistemology
Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosop ...
by
Linda Zagzebski
Linda Trinkaus Zagzebski (born 1946) is an American philosopher. She is the Emerita George Lynn Cross Research Professor, as well as Emerita Kingfisher College Chair of the Philosophy of Religion and Ethics, at the University of Oklahoma. She wr ...
, Wayne Riggs, and
Richard Swinburne
Richard Granville Swinburne (IPA ) (born December 26, 1934) is an English philosopher. He is an Emeritus Professor of Philosophy at the University of Oxford. Over the last 50 years Swinburne has been a proponent of philosophical arguments for t ...
, among others. Zagzebski analogizes the value of knowledge to the value of espresso produced by an espresso maker: "The liquid in this cup is not improved by the fact that it comes from a reliable espresso maker. If the espresso tastes good, it makes no difference if it comes from an unreliable machine." For Zagzebski, the value of knowledge deflates to the value of mere true belief. She assumes that reliability in itself has no value or disvalue, but Goldman and Olsson disagree. They point out that Zagzebski's conclusion rests on the assumption of veritism: all that matters is the acquisition of true belief. To the contrary, they argue that a reliable process for acquiring a true belief adds value to the mere true belief by making it more likely that future beliefs of a similar kind will be true. By analogy, having a reliable espresso maker that produced a good cup of espresso would be more valuable than having an unreliable one that luckily produced a good cup because the reliable one would more likely produce good future cups compared to the unreliable one.
The value problem is important to assessing the adequacy of theories of knowledge that conceive of knowledge as consisting of true belief and other components. According to Kvanvig, an adequate account of knowledge should resist counterexamples and allow an explanation of the value of knowledge over mere true belief. Should a theory of knowledge fail to do so, it would prove inadequate.
One of the more influential responses to the problem is that knowledge is not particularly valuable and is not what ought to be the main focus of epistemology. Instead, epistemologists ought to focus on other mental states, such as understanding. Advocates of virtue epistemology have argued that the value of knowledge comes from an internal relationship between the knower and the mental state of believing.
Acquiring knowledge
Sources of knowledge
There are many proposed sources of knowledge and justified belief which we take to be actual sources of knowledge in our everyday lives. Some of the most commonly discussed include
perception
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...
,
reason
Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
, and
testimony
In law and in religion, testimony is a solemn attestation as to the truth of a matter.
Etymology
The words "testimony" and "testify" both derive from the Latin word ''testis'', referring to the notion of a disinterested third-party witness.
La ...
.
Important distinctions
''A priori''–''a posteriori'' distinction
As mentioned above, epistemologists draw a distinction between what can be known ''
a priori
("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...
'' (independently of experience) and what can only be known ''
a posteriori
("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...
'' (through experience). Much of what we call ''a priori'' knowledge is thought to be attained through reason alone, as featured prominently in
rationalism
In philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification".Lacey, A.R. (1996), ''A Dictionary of Philosophy' ...
. This might also include a non-rational faculty of
intuition
Intuition is the ability to acquire knowledge without recourse to conscious reasoning. Different fields use the word "intuition" in very different ways, including but not limited to: direct access to unconscious knowledge; unconscious cognition; ...
, as defended by proponents of
innatism
Innatism is a philosophical and epistemological doctrine that the mind is born with ideas, knowledge, and beliefs. Therefore, the mind is not a ''tabula rasa'' (blank slate) at birth, which contrasts with the views of early empiricists such as ...
. In contrast, ''a posteriori'' knowledge is derived entirely through experience or as a result of experience, as emphasized in
empiricism
In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...
. This also includes cases where knowledge can be traced back to an earlier experience, as in memory or testimony.
A way to look at the difference between the two is through an example. Bruce Russell gives two propositions in which the reader decides which one he believes more. Option A: All crows are birds. Option B: All crows are black. If you believe option A, then you are a priori justified in believing it because you don't have to see a crow to know it's a bird. If you believe in option B, then you are posteriori justified to believe it because you have seen many crows therefore knowing they are black. He goes on to say that it doesn't matter if the statement is true or not, only that if you believe in one or the other that matters.
The idea of ''a priori'' knowledge is that it is based on intuition or rational insights. Laurence BonJour says in his article "The Structure of Empirical Knowledge", that a "rational insight is an immediate, non-inferential grasp, apprehension or 'seeing' that some proposition is necessarily true." (3) Going back to the crow example, by Laurence BonJour's definition the reason you would believe in option A is because you have an immediate knowledge that a crow is a bird, without ever experiencing one.
Evolutionary psychology
Evolutionary psychology is a theoretical approach in psychology that examines cognition and behavior from a modern evolutionary perspective. It seeks to identify human psychological adaptations with regards to the ancestral problems they evolv ...
takes a novel approach to the problem. It says that there is an innate predisposition for certain types of learning. "Only small parts of the brain resemble a
tabula rasa
''Tabula rasa'' (; "blank slate") is the theory that individuals are born without built-in mental content, and therefore all knowledge comes from experience or perception. Epistemological proponents of ''tabula rasa'' disagree with the doctri ...
; this is true even for human beings. The remainder is more like an exposed negative waiting to be dipped into a developer fluid".
Analytic–synthetic distinction
Immanuel Kant
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and ...
, in his '' Critique of Pure Reason'', drew a distinction between "analytic" and "synthetic" propositions. He contended that some propositions are such that we can know they are true just by understanding their meaning. For example, consider, "My father's brother is my uncle." We can know it is true solely by virtue of our understanding in what its terms mean. Philosophers call such propositions "analytic". Synthetic propositions, on the other hand, have distinct subjects and predicates. An example would be, "My father's brother has black hair." Kant stated that all mathematical and scientific statements are analytic priori propositions because they are
necessarily true
Logical truth is one of the most fundamental concepts in logic. Broadly speaking, a logical truth is a statement which is true regardless of the truth or falsity of its constituent propositions. In other words, a logical truth is a statement whic ...
but our knowledge about the attributes of the mathematical or physical subjects we can only get by logical inference.
While this distinction is first and foremost about meaning and is therefore most relevant to the
philosophy of language
In analytic philosophy, philosophy of language investigates the nature of language and the relations between language, language users, and the world. Investigations may include inquiry into the nature of meaning, intentionality, reference, ...
, the distinction has significant epistemological consequences, seen most prominently in the works of the
logical positivists
Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
. In particular, if the set of propositions which can only be known ''a posteriori'' is coextensive with the set of propositions which are synthetically true, and if the set of propositions which can be known ''a priori'' is coextensive with the set of propositions which are analytically true (or in other words, which are true by definition), then there can only be two kinds of successful inquiry: Logico-mathematical inquiry, which investigates what is true by definition, and empirical inquiry, which investigates what is true in the world. Most notably, this would exclude the possibility that branches of philosophy like
metaphysics
Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
could ever provide informative accounts of what actually exists.
The American philosopher
Willard Van Orman Quine
Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic tradition, recognized as "one of the most influential philosophers of the twentieth century". ...
, in his paper "
Two Dogmas of Empiricism
"Two Dogmas of Empiricism" is a paper by analytic philosopher Willard Van Orman Quine published in 1951. According to University of Sydney professor of philosophy Peter Godfrey-Smith, this "paper ssometimes regarded as the most important in all ...
", famously challenged the analytic-synthetic distinction, arguing that the boundary between the two is too blurry to provide a clear division between propositions that are true by definition and propositions that are not. While some contemporary philosophers take themselves to have offered more sustainable accounts of the distinction that are not vulnerable to Quine's objections, there is no consensus about whether or not these succeed.
Science as knowledge acquisition
Science is often considered to be a refined, formalized, systematic, institutionalized form of the pursuit and acquisition of empirical knowledge. As such, the
philosophy of science
Philosophy of science is a branch of philosophy concerned with the foundations, methods, and implications of science. The central questions of this study concern what qualifies as science, the reliability of scientific theories, and the ultim ...
may be viewed variously as an application of the principles of epistemology or as a foundation for epistemological inquiry.
The regress problem
The
regress problem
In epistemology, the regress argument is the argument that any proposition requires a justification. However, any justification itself requires support. This means that any proposition whatsoever can be endlessly (infinitely) questioned, result ...
(also known as Agrippa's Trilemma) is the problem of providing a complete logical foundation for human knowledge. The traditional way of supporting a rational argument is to appeal to other rational arguments, typically using chains of reason and rules of logic. A classic example that goes back to Aristotle is deducing that ''Socrates is mortal''. We have a logical rule that says ''All humans are mortal'' and an assertion that ''Socrates is human'' and we deduce that ''Socrates is mortal''. In this example how do we know that Socrates is human? Presumably we apply other rules such as: ''All born from human females are human''. Which then leaves open the question how do we know that all born from humans are human? This is the regress problem: how can we eventually terminate a logical argument with some statements that do not require further justification but can still be considered rational and justified? As John Pollock stated:
... to justify a belief one must appeal to a further justified belief. This means that one of two things can be the case. Either there are some beliefs that we can be justified for holding, without being able to justify them on the basis of any other belief, or else for each justified belief there is an infinite regress of (potential) justification
he nebula theory
He or HE may refer to:
Language
* He (pronoun), an English pronoun
* He (kana), the romanization of the Japanese kana へ
* He (letter), the fifth letter of many Semitic alphabets
* He (Cyrillic), a letter of the Cyrillic script called ''He'' in ...
On this theory there is no rock bottom of justification. Justification just meanders in and out through our network of beliefs, stopping nowhere.
p. 26.
The apparent impossibility of completing an infinite chain of reasoning is thought by some to support
skepticism
Skepticism, also spelled scepticism, is a questioning attitude or doubt toward knowledge claims that are seen as mere belief or dogma. For example, if a person is skeptical about claims made by their government about an ongoing war then the pe ...
. It is also the impetus for Descartes's famous dictum: ''
I think, therefore I am
The Latin , usually translated into English as "I think, therefore I am", is the "first principle" of René Descartes's philosophy. He originally published it in French as , in his 1637 ''Discourse on the Method'', so as to reach a wider audienc ...
''. Descartes was looking for some logical statement that could be true without appeal to other statements.
Responses to the regress problem
Many epistemologists studying justification have attempted to argue for various types of chains of reasoning that can escape the regress problem.
Foundationalism
Foundationalists respond to the regress problem by asserting that certain "foundations" or "basic beliefs" support other beliefs but do not themselves require justification from other beliefs. These beliefs might be justified because they are self-evident, infallible, or derive from reliable cognitive mechanisms. Perception, memory, and a priori intuition are often considered possible examples of basic beliefs.
The chief criticism of foundationalism is that if a belief is not supported by other beliefs, accepting it may be arbitrary or unjustified.
Coherentism
Another response to the regress problem is
coherentism
In philosophical epistemology, there are two types of coherentism: the coherence theory of truth; and the coherence theory of justification (also known as epistemic coherentism).
Coherent truth is divided between an anthropological approach, whic ...
, which is the rejection of the assumption that the regress proceeds according to a pattern of linear justification. To avoid the charge of circularity, coherentists hold that an individual belief is justified circularly by the way it fits together (coheres) with the rest of the belief system of which it is a part. This theory has the advantage of avoiding the infinite regress without claiming special, possibly arbitrary status for some particular class of beliefs. Yet, since a system can be coherent while also being wrong, coherentists face the difficulty of ensuring that the whole system corresponds to reality. Additionally, most logicians agree that any argument that is circular is, at best, only trivially valid. That is, to be illuminating, arguments must operate with information from multiple premises, not simply conclude by reiterating a premise.
Nigel Warburton writes in ''Thinking from A to Z'' that " rcular arguments">rcular arguments are not invalid; in other words, from a logical point of view there is nothing intrinsically wrong with them. However, they are, when viciously circular, spectacularly uninformative."
Infinitism
An alternative resolution to the regress problem is known as "
infinitism
Infinitism is the view that knowledge may be justified by an infinite chain of reasons. It belongs to epistemology, the branch of philosophy that considers the possibility, nature, and means of knowledge.
Epistemological infinitism
Since Gettie ...
". Infinitists take the infinite series to be merely potential, in the sense that an individual may have indefinitely many reasons available to them, without having consciously thought through all of these reasons when the need arises. This position is motivated in part by the desire to avoid what is seen as the arbitrariness and circularity of its chief competitors, foundationalism and coherentism. The most prominent defense of infinitism has been given by Peter Klein.
Foundherentism
An intermediate position, known as "
foundherentism
In epistemology, foundherentism is a theory of justification that combines elements from the two rival theories addressing infinite regress, foundationalism prone to arbitrariness, and coherentism prone to circularity (problems raised by the Münc ...
", is advanced by
Susan Haack
Susan Haack (born 1945) is a distinguished professor in the humanities, Cooper Senior Scholar in Arts and Sciences, professor of philosophy, and professor of law at the University of Miami in Coral Gables, Florida.
Haack has written on logic, ...
. Foundherentism is meant to unify foundationalism and coherentism. Haack explains the view by using a crossword puzzle as an analogy. Whereas, for example, infinitists regard the regress of reasons as taking the form of a single line that continues indefinitely, Haack has argued that chains of properly justified beliefs look more like a crossword puzzle, with various different lines mutually supporting each other. Thus, Haack's view leaves room for both chains of beliefs that are "vertical" (terminating in foundational beliefs) and chains that are "horizontal" (deriving their justification from coherence with beliefs that are also members of foundationalist chains of belief).
Schools of thought in epistemology
Empiricism
Empiricism
In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...
is a view in the theory of knowledge which focuses on the role of experience, especially experience based on perceptual observations by the
sense
A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of Stimulus (physiology), stimuli. (For example, in the human body, the brain which is part of the cen ...
s, in the generation of knowledge. Certain forms exempt disciplines such as
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
and
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
from these requirements.
There are many variants of empiricism, including
British empiricism
In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empiri ...
,
logical empiricism
Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
,
phenomenalism
In metaphysics, phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in sp ...
, and some versions of common sense philosophy. Most forms of empiricism give epistemologically privileged status to sensory impressions or
sense data
The theory of sense data is a view in the philosophy of perception, popularly held in the early 20th century by philosophers such as Bertrand Russell, C. D. Broad, H. H. Price, A. J. Ayer, and G. E. Moore. Sense data are taken to be mind-depend ...
, although this plays out very differently in different cases. Some of the most famous historical empiricists include
John Locke
John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenment, Enlightenment thinkers and commonly known as the "father of liberalism ...
,
David Hume
David Hume (; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) Cranston, Maurice, and Thomas Edmund Jessop. 2020 999br>David Hume" ''Encyclopædia Britannica''. Retrieved 18 May 2020. was a Scottish Enlightenment philo ...
,
George Berkeley
George Berkeley (; 12 March 168514 January 1753) – known as Bishop Berkeley (Bishop of Cloyne of the Anglican Church of Ireland) – was an Anglo-Irish philosopher whose primary achievement was the advancement of a theory he called "immate ...
,
Francis Bacon
Francis Bacon, 1st Viscount St Alban (; 22 January 1561 – 9 April 1626), also known as Lord Verulam, was an English philosopher and statesman who served as Attorney General and Lord Chancellor of England. Bacon led the advancement of both ...
,
John Stuart Mill
John Stuart Mill (20 May 1806 – 7 May 1873) was an English philosopher, political economist, Member of Parliament (MP) and civil servant. One of the most influential thinkers in the history of classical liberalism, he contributed widely to ...
,
Rudolf Carnap
Rudolf Carnap (; ; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. He ...
, and
Bertrand Russell
Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, ...
.
Rationalism
Rationalism is the epistemological view that reason is the chief source of knowledge and the main determinant of what constitutes knowledge. More broadly, it can also refer to any view which appeals to reason as a source of knowledge or justification. Rationalism is one of the two classical views in epistemology, the other being empiricism. Rationalists claim that the mind, through the use of reason, can directly grasp certain truths in various domains, including
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
,
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
,
ethics
Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns m ...
, and
metaphysics
Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
. Rationalist views can range from modest views in mathematics and logic (such as that of
Gottlob Frege
Friedrich Ludwig Gottlob Frege (; ; 8 November 1848 – 26 July 1925) was a German philosopher, logician, and mathematician. He was a mathematics professor at the University of Jena, and is understood by many to be the father of analytic phil ...
) to ambitious metaphysical systems (such as that of
Baruch Spinoza
Baruch (de) Spinoza (born Bento de Espinosa; later as an author and a correspondent ''Benedictus de Spinoza'', anglicized to ''Benedict de Spinoza''; 24 November 1632 – 21 February 1677) was a Dutch philosopher of Portuguese-Jewish origin, b ...
).
Some of the most famous rationalists include
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
,
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathem ...
,
Baruch Spinoza
Baruch (de) Spinoza (born Bento de Espinosa; later as an author and a correspondent ''Benedictus de Spinoza'', anglicized to ''Benedict de Spinoza''; 24 November 1632 – 21 February 1677) was a Dutch philosopher of Portuguese-Jewish origin, b ...
, and
Gottfried Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mathem ...
.
Skepticism
Skepticism is a position that questions the possibility of human knowledge, either in particular domains or on a general level. Skepticism does not refer to any one specific school of philosophy, but is rather a thread that runs through many epistemological debates. Ancient Greek skepticism began during the Hellenistic period in philosophy, which featured both
Pyrrhonism
Pyrrhonism is a school of philosophical skepticism founded by Pyrrho in the fourth century BCE. It is best known through the surviving works of Sextus Empiricus, writing in the late second century or early third century CE.
History
Pyrrho of E ...
(notably defended by
Pyrrho
Pyrrho of Elis (; grc, Πύρρων ὁ Ἠλεῖος, Pyrrhо̄n ho Ēleios; ), born in Elis, Greece, was a Greek philosopher of Classical antiquity, credited as being the first Greek skeptic philosopher and founder of Pyrrhonism.
Life
...
,
Sextus Empiricus
Sextus Empiricus ( grc-gre, Σέξτος Ἐμπειρικός, ; ) was a Ancient Greece, Greek Pyrrhonism, Pyrrhonist philosopher and Empiric school physician. His philosophical works are the most complete surviving account of ancient Greek and ...
, and
Aenesidemus
Aenesidemus ( grc, Αἰνησίδημος or Αἰνεσίδημος) was a Greek Pyrrhonist philosopher, born in Knossos on the island of Crete. He lived in the 1st century BC, taught in Alexandria and flourished shortly after the life of Cic ...
) and
Academic skepticism
Academic skepticism refers to the skeptical period of ancient Platonism dating from around 266 BCE, when Arcesilaus became scholarch of the Platonic Academy, until around 90 BCE, when Antiochus of Ascalon rejected skepticism, although individua ...
(notably defended by
Arcesilaus
Arcesilaus (; grc-gre, Ἀρκεσίλαος; 316/5–241/0 BC) was a Greek Hellenistic philosopher. He was the founder of Academic Skepticism and what is variously called the Second or Middle or New Academy – the phase of the Platonic Acade ...
and
Carneades
Carneades (; el, Καρνεάδης, ''Karneadēs'', "of Carnea"; 214/3–129/8 BC) was a Greek philosopher and perhaps the most prominent head of the Skeptical Academy in ancient Greece. He was born in Cyrene. By the year 159 BC, he had begu ...
). Among ancient Indian philosophers, skepticism was notably defended by the
Ajñana
''Ajñāna'' () was one of the ''nāstika'' or "heterodox" schools of ancient Indian philosophy, and the ancient school of radical Indian skepticism. It was a Śramaṇa movement and a major rival of early Buddhism, Jainism and the Ājīvika ...
school and in the Buddhist
Madhyamika
Mādhyamaka ("middle way" or "centrism"; ; Tibetan: དབུ་མ་པ ; ''dbu ma pa''), otherwise known as Śūnyavāda ("the emptiness doctrine") and Niḥsvabhāvavāda ("the no ''svabhāva'' doctrine"), refers to a tradition of Buddhist ...
tradition. In modern philosophy,
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathem ...
' famous inquiry into mind and body began as an exercise in skepticism, in which he started by trying to doubt all purported cases of knowledge in order to search for something that was known with absolute
certainty
Certainty (also known as epistemic certainty or objective certainty) is the epistemic property of beliefs which a person has no rational grounds for doubting. One standard way of defining epistemic certainty is that a belief is certain if and ...
.
Epistemic skepticism questions whether knowledge is possible at all. Generally speaking, skeptics argue that knowledge requires
certainty
Certainty (also known as epistemic certainty or objective certainty) is the epistemic property of beliefs which a person has no rational grounds for doubting. One standard way of defining epistemic certainty is that a belief is certain if and ...
, and that most or all of our beliefs are
fallible
Originally, fallibilism (from Medieval Latin: ''fallibilis'', "liable to err") is the philosophical principle that propositions can be accepted even though they cannot be conclusively proven or justified,Haack, Susan (1979)"Fallibilism and Nece ...
(meaning that our grounds for holding them always, or almost always, fall short of certainty), which would together entail that knowledge is always or almost always
impossible
Impossible, Imposible or Impossibles may refer to:
Music
* ''ImPossible'' (album), a 2016 album by Divinity Roxx
* ''The Impossible'' (album)
Groups
* The Impossibles (American band), a 1990s indie-ska group from Austin, Texas
* The Impossibl ...
for us. Characterizing knowledge as strong or weak is dependent on a person's viewpoint and their characterization of knowledge. Much of modern epistemology is derived from attempts to better understand and address philosophical skepticism.
Pyrrhonism
One of the oldest forms of epistemic skepticism can be found in Agrippa's trilemma (named after the
Pyrrhonist
Pyrrho of Elis (; grc, Πύρρων ὁ Ἠλεῖος, Pyrrhо̄n ho Ēleios; ), born in Elis, Greece, was a Greek philosopher of Classical antiquity, credited as being the first Greek skeptic philosopher and founder of Pyrrhonism.
Life
...
philosopher
Agrippa the Skeptic
Agrippa ( el, Ἀγρίππας) was a Pyrrhonist philosopher who probably lived towards the end of the 1st century CE. He is regarded as the author of "The Five Tropes (or Modes, in el, τρόποι) of Agrippa", which are purported to esta ...
) which demonstrates that certainty can not be achieved with regard to beliefs. Pyrrhonism dates back to
Pyrrho of Elis
Pyrrho of Elis (; grc, Πύρρων ὁ Ἠλεῖος, Pyrrhо̄n ho Ēleios; ), born in Elis, Greece, was a Greek philosopher of Classical antiquity, credited as being the first Greek skeptic philosopher and founder of Pyrrhonism.
Life
...
from the 4th century BCE, although most of what we know about Pyrrhonism today is from the surviving works of
Sextus Empiricus
Sextus Empiricus ( grc-gre, Σέξτος Ἐμπειρικός, ; ) was a Ancient Greece, Greek Pyrrhonism, Pyrrhonist philosopher and Empiric school physician. His philosophical works are the most complete surviving account of ancient Greek and ...
. Pyrrhonists claim that for any argument for a non-evident proposition, an equally convincing argument for a contradictory proposition can be produced. Pyrrhonists do not dogmatically deny the possibility of knowledge, but instead point out that beliefs about non-evident matters cannot be substantiated.
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathem ...
, supposes that our sensory impressions may be controlled by some external power rather than the result of ordinary veridical perception. In such a scenario, nothing we sense would actually exist, but would instead be mere illusion. As a result, we would never be able to know anything about the world, since we would be systematically deceived about everything. The conclusion often drawn from evil demon skepticism is that even if we are not completely deceived, all of the information provided by our senses is still ''compatible'' with skeptical scenarios in which we are completely deceived, and that we must therefore either be able to exclude the possibility of deception or else must deny the possibility of ''infallible'' knowledge (that is, knowledge which is completely certain) beyond our immediate sensory impressions. While the view that no beliefs are beyond doubt other than our immediate sensory impressions is often ascribed to Descartes, he in fact thought that we ''can'' exclude the possibility that we are systematically deceived, although his reasons for thinking this are based on a highly contentious
ontological argument
An ontological argument is a philosophical argument, made from an ontological basis, that is advanced in support of the existence of God. Such arguments tend to refer to the state of being or existing. More specifically, ontological arguments ...
for the existence of a benevolent God who would not allow such deception to occur.
Responses to philosophical skepticism
Epistemological skepticism can be classified as either "mitigated" or "unmitigated" skepticism. Mitigated skepticism rejects "strong" or "strict" knowledge claims but does approve weaker ones, which can be considered "virtual knowledge", but only with regard to justified beliefs. Unmitigated skepticism rejects claims of both virtual and strong knowledge. Characterizing knowledge as strong, weak, virtual or genuine can be determined differently depending on a person's viewpoint as well as their characterization of knowledge. Some of the most notable attempts to respond to unmitigated skepticism include
direct realism
Direct may refer to:
Mathematics
* Directed set, in order theory
* Direct limit of (pre), sheaves
* Direct sum of modules, a construction in abstract algebra which combines several vector spaces
Computing
* Direct access (disambiguation), a ...
,
disjunctivism Disjunctivism is a position in the philosophy of perception that rejects the existence of sense data in certain cases. The disjunction is between appearance and the reality behind the appearance "making itself perceptually manifest to someone."
Ve ...
pragmatism
Pragmatism is a philosophical tradition that considers words and thought as tools and instruments for prediction, problem solving, and action, and rejects the idea that the function of thought is to describe, represent, or mirror reality. ...
,
fideism
Fideism () is an epistemological theory which maintains that faith is independent of reason, or that reason and faith are hostile to each other and faith is superior at arriving at particular truths (see natural theology). The word ''fideism'' c ...
, and
fictionalism
Fictionalism is the view in philosophy according to which statements that appear to be descriptions of the world should not be construed as such, but should instead be understood as cases of "make believe", of pretending to treat something as liter ...
.
Pragmatism
Pragmatism
Pragmatism is a philosophical tradition that considers words and thought as tools and instruments for prediction, problem solving, and action, and rejects the idea that the function of thought is to describe, represent, or mirror reality. ...
is a fallibilist epistemology that emphasizes the role of action in knowing. Different interpretations of pragmatism variously emphasize: truth as the final outcome of ideal scientific inquiry and experimentation, truth as closely related to usefulness, experience as transacting with instead of representing nature, and human practices as the foundation of language. Pragmatism's origins are often attributed to
Charles Sanders Peirce
Charles Sanders Peirce ( ; September 10, 1839 – April 19, 1914) was an American philosopher, logician, mathematician and scientist who is sometimes known as "the father of pragmatism".
Educated as a chemist and employed as a scientist for t ...
,
William James
William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States.
James is considered to be a leading thinker of the lat ...
, and
John Dewey
John Dewey (; October 20, 1859 – June 1, 1952) was an American philosopher, psychologist, and educational reformer whose ideas have been influential in education and social reform. He was one of the most prominent American scholars in the f ...
. In 1878, Peirce formulated the maxim: "Consider what effects, that might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object."
William James suggested that through a pragmatist epistemology, theories "become instruments, not answers to enigmas in which we can rest". In James's pragmatic method, which he adapted from Peirce, metaphysical disputes can be settled by tracing the practical consequences of the different sides of the argument. If this process does not resolve the dispute, then "the dispute is idle".
Contemporary versions of pragmatism have been developed by thinkers such as
Richard Rorty
Richard McKay Rorty (October 4, 1931 – June 8, 2007) was an American philosopher. Educated at the University of Chicago and Yale University, he had strong interests and training in both the history of philosophy and in contemporary analytic phi ...
and
Hilary Putnam
Hilary Whitehall Putnam (; July 31, 1926 – March 13, 2016) was an American philosopher, mathematician, and computer scientist, and a major figure in analytic philosophy in the second half of the 20th century. He made significant contributions ...
. Rorty proposed that values were historically contingent and dependent upon their utility within a given historical period. Contemporary philosophers working in pragmatism are called neopragmatists, and also include
Nicholas Rescher
Nicholas Rescher (; ; born 15 July 1928) is a German-American philosopher, polymath, and author, who has been a professor of philosophy at the University of Pittsburgh since 1961. He is chairman of the Center for Philosophy of Science and was for ...
,
Robert Brandom
Robert Boyce Brandom (born March 13, 1950) is an American philosopher who teaches at the University of Pittsburgh. He works primarily in philosophy of language, philosophy of mind and philosophical logic, and his academic output manifests both sys ...
,
Susan Haack
Susan Haack (born 1945) is a distinguished professor in the humanities, Cooper Senior Scholar in Arts and Sciences, professor of philosophy, and professor of law at the University of Miami in Coral Gables, Florida.
Haack has written on logic, ...
, and
Cornel West
Cornel Ronald West (born June 2, 1953) is an American philosopher, political activist, social critic, actor, and public intellectual. The grandson of a Baptist minister, West focuses on the role of race, gender, and class in American society and ...
.
Naturalized epistemology
In certain respects an intellectual descendant of pragmatism,
naturalized epistemology
Naturalized epistemology (a term coined by W. V. O. Quine) is a collection of philosophic views concerned with the theory of knowledge that emphasize the role of natural scientific methods. This shared emphasis on scientific methods of studying kn ...
considers the evolutionary role of knowledge for agents living and evolving in the world. It de-emphasizes the questions around justification and truth, and instead asks, empirically, how reliable beliefs are formed and the role that evolution played in the development of such processes. It suggests a more empirical approach to the subject as a whole, leaving behind philosophical definitions and consistency arguments, and instead using psychological methods to study and understand how "knowledge" is actually formed and is used in the natural world. As such, it does not attempt to answer the analytic questions of traditional epistemology, but rather replace them with new empirical ones.
Naturalized epistemology was first proposed in "Epistemology Naturalized", a seminal paper by
W.V.O. Quine
Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic tradition, recognized as "one of the most influential philosophers of the twentieth century". ...
. A less radical view has been defended by
Hilary Kornblith
Hilary Kornblith is an American philosopher. He is a professor of philosophy at the University of Massachusetts Amherst and one of contemporary epistemology's most prominent proponents of naturalized epistemology.
Biography
Kornblith received his ...
in ''Knowledge and its Place in Nature'', in which he seeks to turn epistemology towards empirical investigation without completely abandoning traditional epistemic concepts.
Epistemic relativism
Epistemic relativism is the view that what is true, rational, or justified for one person need not be true, rational, or justified for another person. Epistemic relativists therefore assert that while there are ''relative'' facts about truth, rationality, justification, and so on, there is no ''perspective-independent'' fact of the matter. Note that this is distinct from epistemic
contextualism
Contextualism, also known as epistemic contextualism, is a family of views in philosophy which emphasize the ''context'' in which an action, utterance, or expression occurs. Proponents of contextualism argue that, in some important respect, the a ...
, which holds that the ''meaning'' of epistemic terms vary across contexts (e.g. "I know" might mean something different in everyday contexts and skeptical contexts). In contrast, epistemic relativism holds that the relevant ''facts'' vary, not just linguistic meaning. Relativism about truth may also be a form of
ontological
In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality.
Ontology addresses questions like how entities are grouped into categories and which of these entities exis ...
relativism, insofar as relativists about truth hold that facts about what ''exists'' vary based on perspective.
Epistemic constructivism
Constructivism
Constructivism may refer to:
Art and architecture
* Constructivism (art), an early 20th-century artistic movement that extols art as a practice for social purposes
* Constructivist architecture, an architectural movement in Russia in the 1920s a ...
is a view in philosophy according to which all "knowledge is a compilation of human-made constructions", "not the neutral discovery of an objective truth". Whereas objectivism is concerned with the "object of our knowledge", constructivism emphasizes "how we construct knowledge". Constructivism proposes new definitions for
knowledge
Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...
and
truth
Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs ...
, which emphasize intersubjectivity rather than objectivity, and viability rather than truth. The constructivist point of view is in many ways comparable to certain forms of pragmatism.
Epistemic idealism
Idealism
In philosophy, the term idealism identifies and describes metaphysical perspectives which assert that reality is indistinguishable and inseparable from perception and understanding; that reality is a mental construct closely connected to ide ...
is a broad term referring to both an
ontological
In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality.
Ontology addresses questions like how entities are grouped into categories and which of these entities exis ...
view about the world being in some sense mind-dependent and a corresponding epistemological view that everything we know can be reduced to mental phenomena. First and foremost, "idealism" is a
metaphysical
Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
doctrine. As an epistemological doctrine, idealism shares a great deal with both empiricism and rationalism. Some of the most famous empiricists have been classified as idealists (particularly
Berkeley
Berkeley most often refers to:
*Berkeley, California, a city in the United States
**University of California, Berkeley, a public university in Berkeley, California
* George Berkeley (1685–1753), Anglo-Irish philosopher
Berkeley may also refer ...
), and yet the
subjectivism
Subjectivism is the doctrine that "our own mental activity is the only unquestionable fact of our experience", instead of shared or communal, and that there is no external or objective truth.
The success of this position is historically attribute ...
inherent to idealism also resembles that of Descartes in many respects. Many idealists believe that knowledge is primarily (at least in some areas) acquired by ''a priori'' processes, or that it is
Language, Truth, and Logic
''Language, Truth and Logic'' is a 1936 book about meaning by the philosopher Alfred Jules Ayer, in which the author defines, explains, and argues for the verification principle of logical positivism, sometimes referred to as the ''criterion o ...
''.
* BonJour, Laurence. 2002. ''Epistemology: Classic Problems and Contemporary Responses''. Lanham, MD: Rowman & Littlefield.
* Bovens, Luc & Hartmann, Stephan. 2003. ''Bayesian Epistemology''. Oxford: Oxford University Press.
* Butchvarov, Panayot. 1970. ''The Concept of Knowledge''. Evanston, Northwestern University Press.
*
* Cohen, Stewart. 1999. "Contextualism, Skepticism, and Reasons", in Tomberlin 1999.
* Dancy, Jonathan. 1991. ''An Introduction to Contemporary Epistemology'' (Second Edition). John Wiley & Sons.
*
* DeRose, Keith. 1999. Contextualism: An Explanation and Defense ", in Greco and Sosa 1999.
* Descartes, Rene. 1641. ''
Meditations on First Philosophy
''Meditations on First Philosophy, in which the existence of God and the immortality of the soul are demonstrated'' ( la, Meditationes de Prima Philosophia, in qua Dei existentia et animæ immortalitas demonstratur) is a philosophical treatise ...
''
* Feldman, Richard. 1999. "Contextualism and Skepticism", in Tomberlin 1999, pp. 91–114.
* Gettier, Edmund. 1963. "Is Justified True Belief Knowledge?", ''Analysis'', Vol. 23, pp. 121–123 Online text .
* Greco, J. & Sosa, E. 1999. ''Blackwell Guide to Epistemology'', Blackwell Publishing.
* Harris, Errol E. 1970. ''Hypothesis And Perception'', George Allen and Unwin, London, Reprinted 2002 Routledge, London.
*
* Hay, Clare. 2008. ''The Theory of Knowledge: A Coursebook'', The Lutterworth Press, Cambridge.
* Hawthorne, John. 2005. "The Case for Closure", ''Contemporary Debates in Epistemology'', Peter Sosa and Matthias Steup (ed.): 26–43.
* Hendricks, Vincent F. 2006. ''Mainstream and Formal Epistemology'', New York:
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press
A university press is an academic publishing hou ...
.
*
Kant, Immanuel
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and aest ...
. 1781. '' Critique of Pure Reason''.
* Keeton, Morris T. 1962. "Empiricism", in ''Dictionary of Philosophy'', Dagobert D. Runes (ed.), Littlefield, Adams, and Company, Totowa, NJ, pp. 89–90.
* Kirkham, Richard. 1984. "Does the Gettier Problem Rest on a Mistake?" ''Mind'', 93.
* Klein, Peter. 1981. ''Certainty: a Refutation of Skepticism'', Minneapolis, MN:
University of Minnesota Press
The University of Minnesota Press is a university press that is part of the University of Minnesota. It had annual revenues of just over $8 million in fiscal year 2018.
Founded in 1925, the University of Minnesota Press is best known for its book ...
.
* Kyburg, H.E. 1961. ''Probability and the Logic of Rational Belief'', Middletown, CT: Wesleyan University Press.
* Korzybski, Alfred. 1994 (1933). ''Science and Sanity: An Introduction to Non-Aristotelian Systems and General Semantics'', Fifth Edition. Ft. Worth, TX: Institute of General Semantics.
*
* Morin, Edgar. 1986. ''La Méthode, Tome 3, La Connaissance de la connaissance'' (Method, 3rd volume : The knowledge of knowledge)
* Morton, Adam. 2002. ''A Guide Through the Theory of Knowledge'' (Third Edition) Oxford: Blackwell Publishing.
* Nelson, Quee. 2007. ''The Slightest Philosophy'', Indianapolis, IN: Dog Ear Publishing, 296 pages.
* Niiniluoto, Ilkka. 2002. ''Critical Scientific Realism'', Oxford: Oxford Univ. Press.
*
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
. ''
Meno
''Meno'' (; grc-gre, Μένων, ''Ménōn'') is a Socratic dialogue by Plato. Meno begins the dialogue by asking Socrates whether virtue is taught, acquired by practice, or comes by nature. In order to determine whether virtue is teachable ...
Scepticism and Animal Faith
''Scepticism and Animal Faith'' (1923) is a later work by Spanish-born American philosopher George Santayana. He intended it to be "merely the introduction to a new system of philosophy," a work that would later be called ''The Realms of Being'', w ...
'', New York: Charles Scribner's Sons – London: Constable and Co.
* Spir, African. 1877. ''Denken und Wirklichkeit: Versuch einer Erneuerung der kritischen Philosophie'' (Thought and Reality: Attempt at a Renewal of Critical Philosophy), (Second Edition) Leipzig: J.G. Findel.
*
* Steup, Matthias. 2005. "Knowledge and Skepticism", ''Contemporary Debates in Epistemology'', Peter Sosa and Matthias Steup (eds.): 1–13.
* Tomberlin, James (ed.). 1999. ''Philosophical Perspectives 13, Epistemology'', Blackwell Publishing.
*
* Wittgenstein, Ludwig. 1922. ''
Tractatus Logico-Philosophicus
The ''Tractatus Logico-Philosophicus'' (widely abbreviated and cited as TLP) is a book-length philosophical work by the Austrian philosopher Ludwig Wittgenstein which deals with the relationship between language and reality and aims to define the ...
'',
Frank P. Ramsey
Frank Plumpton Ramsey (; 22 February 1903 – 19 January 1930) was a British people, British philosopher, mathematician, and economist who made major contributions to all three fields before his death at the age of 26. He was a close friend of L ...
and
C.K. Ogden
Charles Kay Ogden (; 1 June 1889 – 20 March 1957) was an English linguist, philosopher, and writer. Described as a polymath but also an eccentric and outsider, he took part in many ventures related to literature, politics, the arts, and philo ...
;''Stanford Encyclopedia of Philosophy'' articles
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;''Internet Encyclopedia of Philosophy'' articles
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;''Encyclopædia Britannica''
Epistemology by Avrum Stroll and A.P. Martinich
;Other links
* Th London Philosophy Study Guide offers many suggestions on what to read, depending on the student's familiarity with the subject
*
Knowledge-How at Philpapers
*
– a brief introduction to the topic by Keith DeRose.
an by Paul Newall at the Galilean Library.
– Marjorie Clay (ed.), an electronic publication from The Council for Philosophical Studies.
An Introduction to Epistemology by Paul Newall, aimed at beginners.
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