Inductive reasoning is a
method of reasoning
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, lang ...
in which a general
principle
A principle is a proposition or value that is a guide for behavior or evaluation. In law, it is a Legal rule, rule that has to be or usually is to be followed. It can be desirably followed, or it can be an inevitable consequence of something, suc ...
is derived from a body of observations. It consists of making broad generalizations based on specific observations. Inductive reasoning is distinct from
''deductive'' reasoning. If the premises are correct, the conclusion of a deductive argument is ''certain''; in contrast, the truth of the conclusion of an inductive argument is ''
probable
Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking ...
'', based upon the evidence given.
Types
The types of inductive reasoning include generalization, prediction, statistical syllogism, argument from analogy, and causal inference.
Inductive generalization
A generalization (more accurately, an ''inductive generalization'') proceeds from a premise about a
sample
Sample or samples may refer to:
Base meaning
* Sample (statistics), a subset of a population – complete data set
* Sample (signal), a digital discrete sample of a continuous analog signal
* Sample (material), a specimen or small quantity of s ...
to a conclusion about the
population
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
.
The observation obtained from this sample is projected onto the broader population.
: The proportion Q of the sample has attribute A.
: Therefore, the proportion Q of the population has attribute A.
For example, say there are 20 balls—either black or white—in an urn. To estimate their respective numbers, you draw a sample of four balls and find that three are black and one is white. An inductive generalization would be that there are 15 black and five white balls in the urn.
How much the premises support the conclusion depends upon (1) the number in the sample group, (2) the number in the population, and (3) the degree to which the sample represents the population (which may be achieved by taking a random sample). The greater the sample size relative to the population and the more closely the sample represents the population, the stronger the generalization is. The
hasty generalization
A faulty generalization is an informal fallacy wherein a conclusion is drawn about all or many instances of a phenomenon on the basis of one or a few instances of that phenomenon. It is similar to a proof by example in mathematics. It is an examp ...
and the
biased sample
In statistics, sampling bias is a bias in which a sample is collected in such a way that some members of the intended population have a lower or higher sampling probability than others. It results in a biased sample of a population (or non-human f ...
are generalization fallacies.
Statistical generalization
A statistical generalization is a type of inductive argument in which a conclusion about a population is inferred using a
statistically-representative sample. For example:
:Of a sizeable random sample of voters surveyed, 66% support Measure Z.
:Therefore, approximately 66% of voters support Measure Z.
The measure is highly reliable within a well-defined margin of error provided the sample is large and random. It is readily quantifiable. Compare the preceding argument with the following. "Six of the ten people in my book club are Libertarians. Therefore, about 60% of people are Libertarians." The argument is weak because the sample is non-random and the sample size is very small.
Statistical generalizations are also called ''statistical projections'' and ''sample projections''.
Anecdotal generalization
An anecdotal generalization is a type of inductive argument in which a conclusion about a population is inferred using a non-statistical sample. In other words, the generalization is based on
anecdotal evidence
Anecdotal evidence is evidence based only on personal observation, collected in a casual or non-systematic manner. The term is sometimes used in a legal context to describe certain kinds of testimony which are uncorroborated by objective, independ ...
. For example:
:So far, this year his son's Little League team has won 6 of 10 games.
:Therefore, by season's end, they will have won about 60% of the games.
This inference is less reliable (and thus more likely to commit the fallacy of hasty generalization) than a statistical generalization, first, because the sample events are non-random, and second because it is not reducible to mathematical expression. Statistically speaking, there is simply no way to know, measure and calculate the circumstances affecting performance that will occur in the future. On a philosophical level, the argument relies on the presupposition that the operation of future events will mirror the past. In other words, it takes for granted a uniformity of nature, an unproven principle that cannot be derived from the empirical data itself. Arguments that tacitly presuppose this uniformity are sometimes called ''Humean'' after the philosopher who was first to subject them to philosophical scrutiny.
Prediction
An inductive prediction draws a conclusion about a future, current, or past instance from a sample of other instances. Like an inductive generalization, an inductive prediction relies on a data set consisting of specific instances of a phenomenon. But rather than conclude with a general statement, the inductive prediction concludes with a specific statement about the probability that a single instance will (or will not) have an attribute shared (or not shared) by the other instances.
: Proportion Q of observed members of group G have had attribute A.
: Therefore, there is a probability corresponding to Q that other members of group G will have attribute A when next observed.
Statistical syllogism
A statistical
syllogism
A syllogism ( grc-gre, συλλογισμός, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true.
...
proceeds from a generalization about a group to a conclusion about an individual.
:Proportion Q of the known instances of population P has attribute A.
: Individual I is another member of P.
: Therefore, there is a probability corresponding to Q that I has A.
For example:
:90% of graduates from Excelsior Preparatory school go on to University.
:Bob is a graduate of Excelsior Preparatory school.
:Therefore, Bob will go on to University.
This is a ''statistical syllogism''.
[Introduction to Logic. Harry J. Gensler, Rutledge, 2002. p. 268] Even though one cannot be sure Bob will attend university, we can be fully assured of the exact probability of this outcome (given no further information). Arguably the argument is too strong and might be accused of "cheating". After all, the probability is given in the premise. Typically, inductive reasoning seeks to ''formulate'' a
probability
Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and ...
. Two
dicto simpliciter
''Secundum quid'' (also called ''secundum quid et simpliciter'', meaning " hat is truein a certain respect and hat is trueabsolutely")
is a type of informal fallacy that occurs when the arguer fails to recognize the difference between rules of th ...
fallacies can occur in statistical syllogisms: "
accident
An accident is an unintended, normally unwanted event that was not directly caused by humans. The term ''accident'' implies that nobody should be blamed, but the event may have been caused by unrecognized or unaddressed risks. Most researcher ...
" and "
converse accident
The fallacy of converse accident (also called reverse accident, destroying the exception, or ''a dicto secundum quid ad dictum simpliciter'') is an informal fallacy that can occur in a statistical syllogism (an argument based on a generalization) ...
".
Argument from analogy
The process of analogical inference involves noting the shared properties of two or more things and from this basis inferring that they also share some further property:
:P and Q are similar with respect to properties a, b, and c.
:Object P has been observed to have further property x.
:Therefore, Q probably has property x also.
Analogical reasoning is very frequent in
common sense
''Common Sense'' is a 47-page pamphlet written by Thomas Paine in 1775–1776 advocating independence from Great Britain to people in the Thirteen Colonies. Writing in clear and persuasive prose, Paine collected various moral and political argu ...
,
science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
,
philosophy
Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...
,
law
Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vario ...
, and the
humanities
Humanities are academic disciplines that study aspects of human society and culture. In the Renaissance, the term contrasted with divinity and referred to what is now called classics, the main area of secular study in universities at the t ...
, but sometimes it is accepted only as an auxiliary method. A refined approach is
case-based reasoning
In artificial intelligence and philosophy, case-based reasoning (CBR), broadly construed, is the process of solving new problems based on the solutions of similar past problems.
In everyday life, an auto mechanic who fixes an engine by recalli ...
.
:Mineral A and Mineral B are both igneous rocks often containing veins of quartz and are most commonly found in South America in areas of ancient volcanic activity.
:Mineral A is also a soft stone suitable for carving into jewelry.
:Therefore, mineral B is probably a soft stone suitable for carving into jewelry.
This is ''analogical induction'', according to which things alike in certain ways are more prone to be alike in other ways. This form of induction was explored in detail by philosopher John Stuart Mill in his ''System of Logic'', where he states, "
ere can be no doubt that every resemblance
ot known to be irrelevantaffords some degree of probability, beyond what would otherwise exist, in favor of the conclusion." See
Mill's Methods
Mill's Methods are five methods of induction described by philosopher John Stuart Mill in his 1843 book ''A System of Logic''. They are intended to illuminate issues of causation.
The methods
Direct method of agreement
For a property to be a ...
.
Some thinkers contend that analogical induction is a subcategory of inductive generalization because it assumes a pre-established uniformity governing events. Analogical induction requires an auxiliary examination of the ''relevancy'' of the characteristics cited as common to the pair. In the preceding example, if a premise were added stating that both stones were mentioned in the records of early Spanish explorers, this common attribute is extraneous to the stones and does not contribute to their probable affinity.
A pitfall of analogy is that features can be
cherry-picked
Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position while ignoring a significant portion of related and similar cases or data th ...
: while objects may show striking similarities, two things juxtaposed may respectively possess other characteristics not identified in the analogy that are characteristics sharply ''dis''similar. Thus, analogy can mislead if not all relevant comparisons are made.
Causal inference
A causal inference draws a conclusion about a causal connection based on the conditions of the occurrence of an effect. Premises about the correlation of two things can indicate a causal relationship between them, but additional factors must be confirmed to establish the exact form of the causal relationship.
Methods
The two principal methods used to reach inductive conclusions are ''enumerative induction'' and ''eliminative induction.''
Enumerative induction
Enumerative induction is an inductive method in which a conclusion is constructed based on the ''number'' of instances that support it. The more supporting instances, the stronger the conclusion.
The most basic form of enumerative induction reasons from particular instances to all instances, and is thus an unrestricted generalization. If one observes 100 swans, and all 100 were white, one might infer a universal
categorical proposition
In logic, a categorical proposition, or categorical statement, is a proposition that asserts or denies that all or some of the members of one category (the ''subject term'') are included in another (the ''predicate term''). The study of arguments ...
of the form ''All swans are white''. As this
reasoning form's premises, even if true, do not entail the conclusion's truth, this is a form of inductive inference. The conclusion might be true, and might be thought probably true, yet it can be false. Questions regarding the justification and form of enumerative inductions have been central in
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 ...
, as enumerative induction has a pivotal role in the traditional model of the
scientific method
The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific m ...
.
:All life forms so far discovered are composed of cells.
:Therefore, all life forms are composed of cells.
This is ''enumerative induction'', also known as ''simple induction'' or ''simple predictive induction''. It is a subcategory of inductive generalization. In everyday practice, this is perhaps the most common form of induction. For the preceding argument, the conclusion is tempting but makes a prediction well in excess of the evidence. First, it assumes that life forms observed until now can tell us how future cases will be: an appeal to uniformity. Second, the conclusion ''All'' is a bold assertion. A single contrary instance foils the argument. And last, quantifying the level of probability in any mathematical form is problematic. By what standard do we measure our Earthly sample of known life against all (possible) life? Suppose we do discover some new organism—such as some microorganism floating in the mesosphere or an asteroid—and it is cellular. Does the addition of this corroborating evidence oblige us to raise our probability assessment for the subject proposition? It is generally deemed reasonable to answer this question "yes," and for a good many this "yes" is not only reasonable but incontrovertible. So then just ''how much'' should this new data change our probability assessment? Here, consensus melts away, and in its place arises a question about whether we can talk of probability coherently at all without numerical quantification.
:All life forms so far discovered have been composed of cells.
:Therefore, the ''next'' life form discovered will be composed of cells.
This is enumerative induction in its ''weak form''. It truncates "all" to a mere single instance and, by making a far weaker claim, considerably strengthens the probability of its conclusion. Otherwise, it has the same shortcomings as the strong form: its sample population is non-random, and quantification methods are elusive.
Eliminative induction
Eliminative induction
The Baconian method is the investigative method developed by Sir Francis Bacon, one of the founders of modern science, and thus a first formulation of a modern scientific method. The method was put forward in Bacon's book ''Novum Organum'' (1620), ...
, also called variative induction, is an inductive method in which a conclusion is constructed based on the ''variety'' of instances that support it. Unlike enumerative induction, eliminative induction reasons based on the various kinds of instances that support a conclusion, rather than the number of instances that support it. As the variety of instances increases, the more possible conclusions based on those instances can be identified as incompatible and eliminated. This, in turn, increases the strength of any conclusion that remains consistent with the various instances. This type of induction may use different methodologies such as quasi-experimentation, which tests and where possible eliminates rival hypotheses. Different evidential tests may also be employed to eliminate possibilities that are entertained.
Eliminative induction is crucial to the scientific method and is used to eliminate hypotheses that are inconsistent with observations and experiments.
It focuses on possible causes instead of observed actual instances of causal connections.
History
Ancient philosophy
For a move from particular to universal,
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 ...
in the 300s BCE used the Greek word ''epagogé'', which
Cicero
Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the estab ...
translated into the Latin word ''inductio''.
[Stefano Gattei, ''Karl Popper's Philosophy of Science: Rationality without Foundations'' (New York: ]Routledge
Routledge () is a British multinational publisher. It was founded in 1836 by George Routledge, and specialises in providing academic books, journals and online resources in the fields of the humanities, behavioural science, education, law, and ...
, 2009), ch. 2 "Science and philosophy"
pp. 28–30
Aristotle and the Peripatetic School
Aristotle's ''
Posterior Analytics
The ''Posterior Analytics'' ( grc-gre, Ἀναλυτικὰ Ὕστερα; la, Analytica Posteriora) is a text from Aristotle's ''Organon'' that deals with demonstration, definition, and scientific knowledge. The demonstration is distinguished ...
'' covers the methods of inductive proof in natural philosophy and in the social sciences. The first book of
Posterior Analytics
The ''Posterior Analytics'' ( grc-gre, Ἀναλυτικὰ Ὕστερα; la, Analytica Posteriora) is a text from Aristotle's ''Organon'' that deals with demonstration, definition, and scientific knowledge. The demonstration is distinguished ...
describes the nature and science of demonstration and its elements: including definition, division, intuitive reason of first principles, particular and universal demonstration, affirmative and negative demonstration, the difference between science and opinion, etc.
Pyrrhonism
The ancient
Pyrrhonists
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 Philosophical skepticism, skeptic philosopher and found ...
were the first Western philosophers to point out the
Problem of induction
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inferen ...
: that induction cannot, according to them, justify the acceptance of universal statements as true.
Ancient medicine
The
Empiric school
The Empiric school of medicine (''Empirics'', ''Empiricists'', or ''Empirici'', el, Ἐμπειρικοί) was a school of medicine founded in Alexandria the middle of the third century BC. The school was a major influence on ancient Greek and Ro ...
of ancient Greek medicine employed ''
epilogism Epilogism is a style of inference used by the ancient Empiric school of medicine. It is a theory-free method that looks at history through the accumulation of facts without major generalization and with consideration of the consequences of making ca ...
'' as a method of inference. 'Epilogism' is a theory-free method that looks at history through the accumulation of facts without major generalization and with consideration of the consequences of making causal claims.
Epilogism is an inference which moves entirely within the domain of visible and evident things, it tries not to invoke
unobservable
An unobservable (also called impalpable) is an entity whose existence, nature, properties, qualities or relations are not directly observable by humans. In philosophy of science, typical examples of "unobservables" are the force of gravity, causat ...
s.
The
Dogmatic school
The Dogmatic school of medicine (''Dogmatics'', or ''Dogmatici'', el, Δογματικοί) was a school of medicine in ancient Greece and Rome. They were the oldest of the medical sects of antiquity. They derived their name from '' dogma'', a ...
of ancient Greek medicine employed ''analogismos'' as a method of inference. This method used analogy to reason from what was observed to unobservable forces.
Early modern philosophy
In 1620,
early modern philosopher 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 ...
repudiated the value of mere experience and enumerative induction alone.
His method of
inductivism
Inductivism is the traditional and still commonplace philosophy of scientific method to develop scientific theories.James Ladyman, ''Understanding Philosophy of Science'' (London & New York: Routledge, 2002), p5158 Inductivism aims to neutrally o ...
required that minute and many-varied observations that uncovered the natural world's structure and causal relations needed to be coupled with enumerative induction in order to have knowledge beyond the present scope of experience. Inductivism therefore required enumerative induction as a component.
David Hume
The empiricist
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 ...
's 1740 stance found enumerative induction to have no rational, let alone logical, basis; instead, induction was the product of instinct rather than reason, a custom of the mind and an everyday requirement to live. While observations, such as the motion of the sun, could be coupled with the principle of the
uniformity of nature
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in ...
to produce conclusions that seemed to be certain, the
problem of induction
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inferen ...
arose from the fact that the uniformity of nature was not a logically valid principle, therefore it could not be defended as deductively rational, but also could not be defended as inductively rational by appealing to the fact that the uniformity of nature has accurately described the past and therefore, will likely accurately describe the future because that is an inductive argument and therefore circular since induction is what needs to be justified.
Since Hume first wrote about the dilemma between the invalidity of deductive arguments and the circularity of inductive arguments in support of the uniformity of nature, this supposed dichotomy between merely two modes of inference, deduction and induction, has been contested with the discovery of a third mode of inference known as abduction, or
abductive reasoning
Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference formulated and advanced by American philosopher Charles Sanders Peirce beginning in the last third of the 19th century ...
, which was first formulated and advanced by
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 ...
, in 1886, where he referred to it as "reasoning by hypothesis." Inference to the best explanation is often yet arguably treated as synonymous to abduction as it was first identified by Gilbert Harman in 1965 where he referred to it as "abductive reasoning," yet his definition of abduction slightly differs from Pierce's definition. Regardless, if abduction is in fact a third mode of inference rationally independent from the other two, then either the uniformity of nature can be rationally justified through abduction, or Hume's dilemma is more of a trilemma. Hume was also skeptical of the application of enumerative induction and reason to reach certainty about unobservables and especially the inference of causality from the fact that modifying an aspect of a relationship prevents or produces a particular outcome.
Immanuel Kant
Awakened from "dogmatic slumber" by a German translation of Hume's work,
Kant
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German Philosophy, philosopher and one of the central Age of Enlightenment, Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemolo ...
sought to explain the possibility of
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 ...
. In 1781, Kant's ''
Critique of Pure Reason'' introduced ''
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' ...
'' as a path toward knowledge distinct from ''
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 ...
''. Kant sorted statements into two types.
Analytic statements are true by virtue of the
arrangement
In music, an arrangement is a musical adaptation of an existing composition. Differences from the original composition may include reharmonization, melodic paraphrasing, orchestration, or formal development. Arranging differs from orches ...
of their terms and
meanings, thus analytic statements are
tautologies, merely logical truths, true by
necessity
Necessary or necessity may refer to:
* Need
** An action somebody may feel they must do
** An important task or essential thing to do at a particular time or by a particular moment
* Necessary and sufficient condition, in logic, something that i ...
. Whereas
synthetic statements hold meanings to refer to states of facts,
contingencies
The American Academy of Actuaries, also known as the Academy, is the body that represents and unites United States actuaries in all practice areas. Established in 1965, the Academy serves as the profession's voice on public policy and professional ...
. Against both rationalist philosophers like
Descartes and
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 mathema ...
as well as against empiricist philosophers like
Locke and
Hume, Kant's ''
Critique of Pure Reason'' is a sustained argument that in order to have knowledge we need both a contribution of our mind (concepts) as well as a contribution of our senses (intuitions). Knowledge proper is for Kant thus restricted to what we can possibly perceive (''
phenomena
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...
''), whereas objects of mere thought ("
things in themselves") are in principle unknowable due to the impossibility of ever perceiving them.
Reasoning that the mind must contain its own categories for organizing
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 ...
, making experience of objects in ''space'' and ''time (
phenomena
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...
)'' possible, Kant concluded that the
uniformity of nature
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in ...
was an ''a priori'' truth.
A class of synthetic statements that was not
contingent
Contingency or Contingent may refer to:
* Contingency (philosophy), in philosophy and logic
* Contingency plan, in planning
* Contingency table, in statistics
* Contingency theory, in organizational theory
* Contingency theory (biology) in evoluti ...
but true by necessity, was then
synthetic ''a priori''. Kant thus saved both
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 ...
and
Newton's law of universal gravitation
Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distanc ...
. On the basis of the argument that what goes beyond our knowledge is "nothing to us," he discarded
scientific realism
Scientific realism is the view that the universe described by science is real regardless of how it may be interpreted.
Within philosophy of science, this view is often an answer to the question "how is the success of science to be explained?" Th ...
. Kant's position that knowledge comes about by a cooperation of perception and our capacity to think (
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 ...
) gave birth to the movement of
German idealism
German idealism was a philosophical movement that emerged in Germany in the late 18th and early 19th centuries. It developed out of the work of Immanuel Kant in the 1780s and 1790s, and was closely linked both with Romanticism and the revolutionary ...
.
Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of modern Western philosophy. His influence extends a ...
's
absolute idealism
Absolute idealism is an ontologically monistic philosophy chiefly associated with G. W. F. Hegel and Friedrich Schelling, both of whom were German idealist philosophers in the 19th century. The label has also been attached to others such as Josi ...
subsequently flourished across continental Europe and England.
Late modern philosophy
Positivism
Positivism is an empiricist philosophical theory that holds that all genuine knowledge is either true by definition or positive—meaning ''a posteriori'' facts derived by reason and logic from sensory experience.John J. Macionis, Linda M. G ...
, developed by
Henri de Saint-Simon
Claude Henri de Rouvroy, comte de Saint-Simon (17 October 1760 – 19 May 1825), often referred to as Henri de Saint-Simon (), was a French political, economic and socialist theorist and businessman whose thought had a substantial influence on p ...
and promulgated in the 1830s by his former student
Auguste Comte
Isidore Marie Auguste François Xavier Comte (; 19 January 1798 – 5 September 1857) was a French philosopher and writer who formulated the doctrine of positivism. He is often regarded as the first philosopher of science in the modern sense ...
, was the first
late modern 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 ...
. In the aftermath of the
French Revolution
The French Revolution ( ) was a period of radical political and societal change in France that began with the Estates General of 1789 and ended with the formation of the French Consulate in November 1799. Many of its ideas are considere ...
, fearing society's ruin, Comte opposed
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 ...
. Human knowledge had evolved from religion to metaphysics to science, said Comte, which had flowed from
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 ...
to
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
to
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
to
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
to
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
to
sociology
Sociology is a social science that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of Empirical ...
—in that order—describing increasingly intricate domains. All of society's knowledge had become scientific, with questions of
theology
Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the ...
and of
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 ...
being unanswerable. Comte found enumerative induction reliable as a consequence of its grounding in available experience. He asserted the use of science, rather than metaphysical truth, as the correct method for the improvement of human society.
According to Comte,
scientific method
The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific m ...
frames predictions, confirms them, and states laws—positive statements—irrefutable by
theology
Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the ...
or by
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 ...
. Regarding experience as justifying enumerative induction by demonstrating the
uniformity of nature
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in ...
,
[Wesley C Salmon]
"The uniformity of Nature"
''Philosophy and Phenomenological Research'', 1953 Sep;14(1):39–48, 9 the British philosopher
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 ...
welcomed Comte's positivism, but thought
scientific laws
Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) ...
susceptible to recall or revision and Mill also withheld from Comte's
Religion of Humanity
Religion of Humanity (from French ''Religion de l'Humanité'' or '' église positiviste'') is a secular religion created by Auguste Comte (1798–1857), the founder of positivist philosophy. Adherents of this religion have built chapels of Huma ...
. Comte was confident in treating
scientific law
Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) ...
as an
irrefutable foundation for all knowledge, and believed that churches, honouring eminent scientists, ought to focus public mindset on ''
altruism
Altruism is the principle and moral practice of concern for the welfare and/or happiness of other human beings or animals, resulting in a quality of life both material and spiritual. It is a traditional virtue in many cultures and a core as ...
''—a term Comte coined—to apply science for humankind's social welfare via
sociology
Sociology is a social science that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of Empirical ...
, Comte's leading science.
During the 1830s and 1840s, while Comte and Mill were the leading philosophers of science,
William Whewell
William Whewell ( ; 24 May 17946 March 1866) was an English polymath, scientist, Anglican priest, philosopher, theologian, and historian of science. He was Master of Trinity College, Cambridge. In his time as a student there, he achieved dist ...
found enumerative induction not nearly as convincing, and, despite the dominance of inductivism, formulated "superinduction".
[Roberto Torretti, ''The Philosophy of Physics'' (Cambridge: ]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 ...
, 1999)
219–21
https://books.google.com/books?id=vg_wxiLRvvYC&pg=PA216 [216]]. Whewell argued that "the peculiar import of the term ''Induction''" should be recognised: "there is some Conception ''superinduced'' upon the facts", that is, "the Invention of a new Conception in every inductive inference". The creation of Conceptions is easily overlooked and prior to Whewell was rarely recognised.
Whewell explained:
These "superinduced" explanations may well be flawed, but their accuracy is suggested when they exhibit what Whewell termed ''
consilience
In science and history, consilience (also convergence of evidence or concordance of evidence) is the principle that evidence from independent, unrelated sources can "converge" on strong conclusions. That is, when multiple sources of evidence are ...
''—that is, simultaneously predicting the inductive generalizations in multiple areas—a feat that, according to Whewell, can establish their truth. Perhaps to accommodate the prevailing view of science as inductivist method, Whewell devoted several chapters to "methods of induction" and sometimes used the phrase "logic of induction", despite the fact that induction lacks rules and cannot be trained.
In the 1870s, the originator of
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. ...
,
C S 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 ...
performed vast investigations that clarified the basis of
deductive inference as a mathematical proof (as, independently, did
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 ...
). Peirce recognized induction but always insisted on a third type of inference that Peirce variously termed ''
abduction'' or ''retroduction'' or ''hypothesis'' or ''presumption''. Later philosophers termed Peirce's abduction, etc., ''
Inference to the Best Explanation
Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference formulated and advanced by American philosopher Charles Sanders Peirce beginning in the last third of the 19th centu ...
'' (IBE).
Contemporary philosophy
Bertrand Russell
Having highlighted Hume's
problem of induction
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inferen ...
,
John Maynard Keynes
John Maynard Keynes, 1st Baron Keynes, ( ; 5 June 1883 – 21 April 1946), was an English economist whose ideas fundamentally changed the theory and practice of macroeconomics and the economic policies of governments. Originally trained in ...
posed ''logical probability'' as its answer, or as near a solution as he could arrive at.
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, ...
found Keynes's ''Treatise on Probability'' the best examination of induction, and believed that if read with
Jean Nicod
Jean George Pierre Nicod (1 June 1893, in France – 16 February 1924, in Geneva, Switzerland) was a French philosopher and logician, best known for his work on propositional logic and inductive reasoning, induction.
Biography
Nicod's main contr ...
's ''Le Probleme logique de l'induction'' as well as
R B Braithwaite's review of Keynes's work in the October 1925 issue of ''Mind'', that would cover "most of what is known about induction", although the "subject is technical and difficult, involving a good deal of mathematics". Two decades later,
Russell proposed enumerative induction as an "independent logical principle".
Russell found:
Gilbert Harman
In a 1965 paper,
Gilbert Harman
Gilbert Harman (May 26, 1938 – November 13, 2021) was an American philosopher, who taught at Princeton University from 1963 until his retirement in 2017. He has published widely in philosophy of language, cognitive science, philosophy of min ...
explained that enumerative induction is not an autonomous phenomenon, but is simply a disguised consequence of Inference to the Best Explanation (IBE).
[Ted Posto]
"Foundationalism"
§ b "Theories of proper inference", §§ iii "Liberal inductivism", ''Internet Encyclopedia of Philosophy
The ''Internet Encyclopedia of Philosophy'' (''IEP'') is a scholarly online encyclopedia, dealing with philosophy, philosophical topics, and philosophers. The IEP combines open access publication with peer reviewed publication of original pape ...
'', 10 Jun 2010 (last updated): "Strict inductivism is motivated by the thought that we have some kind of inferential knowledge of the world that cannot be accommodated by deductive inference from epistemically basic belief
Basic beliefs (also commonly called foundational beliefs or core beliefs) are, under the epistemological view called foundationalism, the axioms of a belief system.
Categories of beliefs
Foundationalism holds that all beliefs must be justifi ...
s. A fairly recent debate has arisen over the merits of strict inductivism. Some philosophers have argued that there are other forms of nondeductive inference that do not fit the model of enumerative induction. C.S. Peirce describes a form of inference called ' abduction' or 'inference to the best explanation
Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference formulated and advanced by American philosopher Charles Sanders Peirce beginning in the last third of the 19th centu ...
'. This form of inference appeals to explanatory considerations to justify belief. One infers, for example, that two students copied answers from a third because this is the best explanation of the available data—they each make the same mistakes and the two sat in view of the third. Alternatively, in a more theoretical context, one infers that there are very small unobservable particles
In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass.
They vary greatly in size or quantity, from s ...
because this is the best explanation of Brownian motion
Brownian motion, or pedesis (from grc, πήδησις "leaping"), is the random motion of particles suspended in a medium (a liquid or a gas).
This pattern of motion typically consists of random fluctuations in a particle's position insi ...
. Let us call 'liberal inductivism' any view that accepts the legitimacy of a form of inference to the best explanation that is distinct from enumerative induction. For a defense of liberal inductivism, see Gilbert Harman
Gilbert Harman (May 26, 1938 – November 13, 2021) was an American philosopher, who taught at Princeton University from 1963 until his retirement in 2017. He has published widely in philosophy of language, cognitive science, philosophy of min ...
's classic (1965) paper. Harman defends a strong version of liberal inductivism according to which enumerative induction is just a disguised form of inference to the best explanation
Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference formulated and advanced by American philosopher Charles Sanders Peirce beginning in the last third of the 19th centu ...
". IBE is otherwise synonymous with
C S 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 ...
's ''abduction''.
Many philosophers of science espousing
scientific realism
Scientific realism is the view that the universe described by science is real regardless of how it may be interpreted.
Within philosophy of science, this view is often an answer to the question "how is the success of science to be explained?" Th ...
have maintained that IBE is the way that scientists develop approximately true scientific theories about nature.
Comparison with deductive reasoning
![Argument terminology used in logic (en)](https://upload.wikimedia.org/wikipedia/commons/a/a4/Argument_terminology_used_in_logic_%28en%29.svg)
Inductive reasoning is a form of argument that—in contrast to deductive reasoning—allows for the possibility that a conclusion can be false, even if all of the
premise
A premise or premiss is a true or false statement that helps form the body of an argument, which logically leads to a true or false conclusion. A premise makes a declarative statement about its subject matter which enables a reader to either agre ...
s are true. This difference between deductive and inductive reasoning is reflected in the terminology used to describe deductive and inductive arguments. In deductive reasoning, an argument is "
valid" when, assuming the argument's premises are true, the conclusion ''must'' be true. If the argument is valid and the premises ''are'' true, then the argument is
"sound". In contrast, in inductive reasoning, an argument's premises can never guarantee that the conclusion ''must'' be true; therefore, inductive arguments can never be valid or sound. Instead, an argument is "strong" when, assuming the argument's premises are true, the conclusion is ''probably'' true. If the argument is strong and the premises ''are'' true, then the argument is "cogent". Less formally, an inductive argument may be called "probable", "plausible", "likely", "reasonable", or "justified", but never "certain" or "necessary". Logic affords no bridge from the probable to the certain.
The futility of attaining certainty through some critical mass of probability can be illustrated with a coin-toss exercise. Suppose someone tests whether a coin is either a fair one or two-headed. They flip the coin ten times, and ten times it comes up heads. At this point, there is a strong reason to believe it is two-headed. After all, the chance of ten heads in a row is .000976: less than one in one thousand. Then, after 100 flips, every toss has come up heads. Now there is “virtual” certainty that the coin is two-headed. Still, one can neither logically nor empirically rule out that the next toss will produce tails. No matter how many times in a row it comes up heads this remains the case. If one programmed a machine to flip a coin over and over continuously at some point the result would be a string of 100 heads. In the fullness of time, all combinations will appear.
As for the slim prospect of getting ten out of ten heads from a fair coin—the outcome that made the coin appear biased—many may be surprised to learn that the chance of any sequence of heads or tails is equally unlikely (e.g., H-H-T-T-H-T-H-H-H-T) and yet it occurs in ''every'' trial of ten tosses. That means ''all'' results for ten tosses have the same probability as getting ten out of ten heads, which is 0.000976. If one records the heads-tails sequences, for whatever result, that exact sequence had a chance of 0.000976.
An argument is deductive when the conclusion is necessary given the premises. That is, the conclusion must be true if the premises are true.
If a deductive conclusion follows duly from its premises, then it is valid; otherwise, it is invalid (that an argument is invalid is not to say it is false; it may have a true conclusion, just not on account of the premises). An examination of the following examples will show that the relationship between premises and conclusion is such that the truth of the conclusion is already implicit in the premises. Bachelors are unmarried because we ''say'' they are; we have defined them so. Socrates is mortal because we have included him in a set of beings that are mortal. The conclusion for a valid deductive argument is already contained in the premises since its truth is strictly a matter of logical relations. It cannot say more than its premises. Inductive premises, on the other hand, draw their substance from fact and evidence, and the conclusion accordingly makes a factual claim or prediction. Its reliability varies proportionally with the evidence. Induction wants to reveal something ''new'' about the world. One could say that induction wants to say ''more'' than is contained in the premises.
To better see the difference between inductive and deductive arguments, consider that it would not make sense to say: "all rectangles so far examined have four right angles, so the next one I see will have four right angles." This would treat logical relations as something factual and discoverable, and thus variable and uncertain. Likewise, speaking deductively we may permissibly say. "All unicorns can fly; I have a unicorn named Charlie; thus Charlie can fly." This deductive argument is valid because the logical relations hold; we are not interested in their factual soundness.
Inductive reasoning is inherently
uncertain. It only deals with the extent to which, given the premises, the conclusion is ''credible'' according to some theory of evidence. Examples include a
many-valued logic
Many-valued logic (also multi- or multiple-valued logic) refers to a propositional calculus in which there are more than two truth values. Traditionally, in Aristotle's logical calculus, there were only two possible values (i.e., "true" and "false" ...
,
Dempster–Shafer theory
The theory of belief functions, also referred to as evidence theory or Dempster–Shafer theory (DST), is a general framework for reasoning with uncertainty, with understood connections to other frameworks such as probability, possibility and i ...
, or
probability theory
Probability theory is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expressing it through a set o ...
with rules for inference such as
Bayes' rule
In probability theory and statistics, Bayes' theorem (alternatively Bayes' law or Bayes' rule), named after Thomas Bayes, describes the probability of an event, based on prior knowledge of conditions that might be related to the event. For examp ...
. Unlike deductive reasoning, it does not rely on universals holding over a
closed domain of discourse to draw conclusions, so it can be applicable even in cases of
epistemic uncertainty (technical issues with this may arise however; for example, the
second axiom of probability is a closed-world assumption).
Another crucial difference between these two types of argument is that deductive certainty is impossible in non-axiomatic systems such as
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 ...
, leaving inductive reasoning as the primary route to (probabilistic) knowledge of such systems.
Given that "if ''A'' is true then that would cause ''B'', ''C'', and ''D'' to be true", an example of deduction would be "''A'' is true therefore we can deduce that ''B'', ''C'', and ''D'' are true". An example of induction would be "''B'', ''C'', and ''D'' are observed to be true therefore ''A'' might be true". ''A'' is a
reasonable explanation for ''B'', ''C'', and ''D'' being true.
For example:
:A large enough asteroid impact would create a very large crater and cause a severe
impact winter
An impact winter is a hypothesized period of prolonged cold weather due to the impact of a large asteroid or comet on the Earth's surface. If an asteroid were to strike land or a shallow body of water, it would eject an enormous amount of dust, ...
that could drive the non-avian dinosaurs to extinction.
:We observe that there is a
very large crater in the Gulf of Mexico dating to very near the time of the extinction of the non-avian dinosaurs.
:Therefore, it is possible that this impact could explain why the non-avian dinosaurs became extinct.
Note, however, that the asteroid explanation for the mass extinction is not necessarily correct. Other events with the potential to affect global climate also coincide with the
extinction of the non-avian dinosaurs. For example, the release of
volcanic gas
Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...
es (particularly
sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
) during the formation of the
Deccan Traps
The Deccan Traps is a large igneous province of west-central India (17–24°N, 73–74°E). It is one of the largest volcanic features on Earth, taking the form of a large shield volcano. It consists of numerous layers of solidified flood ...
in
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
.
Another example of an inductive argument:
:All biological life forms that we know of depend on liquid water to exist.
:Therefore, if we discover a new biological life form, it will probably depend on liquid water to exist.
This argument could have been made every time a new biological life form was found, and would have been correct every time; however, it is still possible that in the future a biological life form not requiring liquid water could be discovered.
As a result, the argument may be stated less formally as:
:All biological life forms that we know of depend on liquid water to exist.
:Therefore, all biological life probably depends on liquid water to exist.
A classical example of an ''incorrect'' inductive argument was presented by John Vickers:
:All of the swans we have seen are white.
:Therefore, we ''know'' that all swans are white.
The correct conclusion would be: we
expect
Expect is an extension to the Tcl scripting language written by Don Libes. The program automates interactions with programs that expose a text terminal interface. Expect, originally written in 1990 for the Unix platform, has since become avail ...
all swans to be white.
Succinctly put: deduction is about ''certainty/necessity''; induction is about ''probability''.
Any single assertion will answer to one of these two criteria. Another approach to the analysis of reasoning is that of
modal logic
Modal logic is a collection of formal systems developed to represent statements about necessity and possibility. It plays a major role in philosophy of language, epistemology, metaphysics, and natural language semantics. Modal logics extend other ...
, which deals with the distinction between the necessary and the ''possible'' in a way not concerned with probabilities among things deemed possible.
The philosophical definition of inductive reasoning is more nuanced than a simple progression from particular/individual instances to broader generalizations. Rather, the premises of an inductive
logical argument
An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialectic ...
indicate some degree of support (inductive probability) for the conclusion but do not
entail
In English common law, fee tail or entail is a form of trust established by deed or settlement which restricts the sale or inheritance of an estate in real property and prevents the property from being sold, devised by will, or otherwise alien ...
it; that is, they suggest truth but do not ensure it. In this manner, there is the possibility of moving from general statements to individual instances (for example, statistical syllogisms).
Note that the definition of ''inductive'' reasoning described here differs from
mathematical induction
Mathematical induction is a method for proving that a statement ''P''(''n'') is true for every natural number ''n'', that is, that the infinitely many cases ''P''(0), ''P''(1), ''P''(2), ''P''(3), ... all hold. Informal metaphors help ...
, which, in fact, is a form of ''deductive'' reasoning. Mathematical induction is used to provide strict proofs of the properties of recursively defined sets. The deductive nature of mathematical induction derives from its basis in a non-finite number of cases, in contrast with the finite number of cases involved in an enumerative induction procedure like
proof by exhaustion
Proof by exhaustion, also known as proof by cases, proof by case analysis, complete induction or the brute force method, is a method of mathematical proof in which the statement to be proved is split into a finite number of cases or sets of equiv ...
. Both mathematical induction and proof by exhaustion are examples of
complete induction
Mathematical induction is a method for proving that a statement ''P''(''n'') is true for every natural number ''n'', that is, that the infinitely many cases ''P''(0), ''P''(1), ''P''(2), ''P''(3), ... all hold. Informal metaphors help ...
. Complete induction is a masked type of deductive reasoning.
Problem of induction
Although philosophers at least as far back as 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
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 ...
have pointed out the unsoundness of inductive reasoning, the classic philosophical critique of the
problem of induction
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inferen ...
was given by the Scottish philosopher
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 ...
. Although the use of inductive reasoning demonstrates considerable success, the justification for its application has been questionable. Recognizing this, Hume highlighted the fact that our mind often draws conclusions from relatively limited experiences that appear correct but which are actually far from certain. In deduction, the truth value of the conclusion is based on the truth of the premise. In induction, however, the dependence of the conclusion on the premise is always uncertain. For example, let us assume that all ravens are black. The fact that there are numerous black ravens supports the assumption. Our assumption, however, becomes invalid once it is discovered that there are white ravens. Therefore, the general rule "all ravens are black" is not the kind of statement that can ever be certain. Hume further argued that it is impossible to justify inductive reasoning: this is because it cannot be justified deductively, so our only option is to justify it inductively. Since this argument is circular, with the help of
Hume's fork he concluded that our use of induction is unjustifiable .
Hume nevertheless stated that even if induction were proved unreliable, we would still have to rely on it. So instead of a position of
severe skepticism, Hume advocated a
practical skepticism based on
common sense
''Common Sense'' is a 47-page pamphlet written by Thomas Paine in 1775–1776 advocating independence from Great Britain to people in the Thirteen Colonies. Writing in clear and persuasive prose, Paine collected various moral and political argu ...
, where the inevitability of induction is accepted.
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, ...
illustrated Hume's skepticism in a story about a chicken, fed every morning without fail, who following the laws of induction concluded that this feeding would always continue, until his throat was eventually cut by the farmer.
In 1963,
Karl Popper
Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the cl ...
wrote, "Induction, ''i.e.'' inference based on many observations, is a myth. It is neither a psychological fact, nor a fact of ordinary life, nor one of scientific procedure."
[Donald Gillies, "Problem-solving and the problem of induction", in ''Rethinking Popper'' (Dordrecht: ]Springer
Springer or springers may refer to:
Publishers
* Springer Science+Business Media, aka Springer International Publishing, a worldwide publishing group founded in 1842 in Germany formerly known as Springer-Verlag.
** Springer Nature, a multinationa ...
, 2009), Zuzana Parusniková & Robert S Cohen, eds
pp. 103–05
Popper's 1972 book ''Objective Knowledge''—whose first chapter is devoted to the problem of induction—opens, "I think I have solved a major philosophical problem: the
problem of induction
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inferen ...
".
In Popper's schema, enumerative induction is "a kind of optical illusion" cast by the steps of conjecture and refutation during a ''problem shift''.
An imaginative leap, the ''tentative solution'' is improvised, lacking inductive rules to guide it.
The resulting, unrestricted generalization is deductive, an entailed consequence of all explanatory considerations.
Controversy continued, however, with Popper's putative solution not generally accepted.
Donald A. Gillies argues that
rules of inferences related to inductive reasoning are overwhelmingly absent from science, and describes most scientific inferences as "involv
ngconjectures thought up by human ingenuity and creativity, and by no means inferred in any mechanical fashion, or according to precisely specified rules."
Gillies also provides a rare counterexample "in the machine learning programs of
AI."
[Donald Gillies, "Problem-solving and the problem of induction", in ''Rethinking Popper'' (Dordrecht: ]Springer
Springer or springers may refer to:
Publishers
* Springer Science+Business Media, aka Springer International Publishing, a worldwide publishing group founded in 1842 in Germany formerly known as Springer-Verlag.
** Springer Nature, a multinationa ...
, 2009), Zuzana Parusniková & Robert S Cohen, eds
p. 111
"I argued earlier that there are some exceptions to Popper's claim that rules of inductive inference do not exist. However, these exceptions are relatively rare. They occur, for example, in the machine learning programs of AI. For the vast bulk of human science both past and present, rules of inductive inference do not exist. For such science, Popper's model of conjectures which are freely invented and then tested out seems to be more accurate than any model based on inductive inferences. Admittedly, there is talk nowadays in the context of science carried out by humans of 'inference to the best explanation' or 'abductive inference', but such so-called inferences are not at all inferences based on precisely formulated rules like the deductive rules of inference. Those who talk of 'inference to the best explanation' or 'abductive inference', for example, never formulate any precise rules according to which these so-called inferences take place. In reality, the 'inferences' which they describe in their examples involve conjectures thought up by human ingenuity and creativity, and by no means inferred in any mechanical fashion, or according to precisely specified rules".
Biases
Inductive reasoning is also known as hypothesis construction because any conclusions made are based on current knowledge and predictions. As with deductive arguments, biases can distort the proper application of inductive argument, thereby preventing the reasoner from forming the most
logical conclusion
Logical consequence (also entailment) is a fundamental concept in logic, which describes the relationship between statements that hold true when one statement logically ''follows from'' one or more statements. A valid logical argument is one ...
based on the clues. Examples of these biases include the
availability heuristic
The availability heuristic, also known as availability bias, is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. This heuristic, operating on the ...
,
confirmation bias
Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values. People display this bias when they select information that supports their views, ignoring ...
, and the
predictable-world bias.
The availability heuristic causes the reasoner to depend primarily upon information that is readily available. People have a tendency to rely on information that is easily accessible in the world around them. For example, in surveys, when people are asked to estimate the percentage of people who died from various causes, most respondents choose the causes that have been most prevalent in the media such as terrorism, murders, and airplane accidents, rather than causes such as disease and traffic accidents, which have been technically "less accessible" to the individual since they are not emphasized as heavily in the world around them.
Confirmation bias is based on the natural tendency to confirm rather than deny a hypothesis. Research has demonstrated that people are inclined to seek solutions to problems that are more consistent with known hypotheses rather than attempt to refute those hypotheses. Often, in experiments, subjects will ask questions that seek answers that fit established hypotheses, thus confirming these hypotheses. For example, if it is hypothesized that Sally is a sociable individual, subjects will naturally seek to confirm the premise by asking questions that would produce answers confirming that Sally is, in fact, a sociable individual.
The predictable-world bias revolves around the inclination to perceive order where it has not been proved to exist, either at all or at a particular level of abstraction. Gambling, for example, is one of the most popular examples of predictable-world bias. Gamblers often begin to think that they see simple and obvious patterns in the outcomes and therefore believe that they are able to predict outcomes based on what they have witnessed. In reality, however, the outcomes of these games are difficult to predict and highly complex in nature. In general, people tend to seek some type of simplistic order to explain or justify their beliefs and experiences, and it is often difficult for them to realise that their perceptions of order may be entirely different from the truth.
Bayesian inference
As a logic of induction rather than a theory of belief,
Bayesian inference
Bayesian inference is a method of statistical inference in which Bayes' theorem is used to update the probability for a hypothesis as more evidence or information becomes available. Bayesian inference is an important technique in statistics, a ...
does not determine which beliefs are ''a priori'' rational, but rather determines how we should rationally change the beliefs we have when presented with evidence. We begin by committing to a
prior probability
In Bayesian statistical inference, a prior probability distribution, often simply called the prior, of an uncertain quantity is the probability distribution that would express one's beliefs about this quantity before some evidence is taken into ...
for a hypothesis based on logic or previous experience and, when faced with evidence, we adjust the strength of our belief in that hypothesis in a precise manner using
Bayesian logic.
Inductive inference
Around 1960,
Ray Solomonoff
Ray Solomonoff (July 25, 1926 – December 7, 2009) was the inventor of algorithmic probability, his General Theory of Inductive Inference (also known as Universal Inductive Inference),Samuel Rathmanner and Marcus Hutter. A philosophical treatise ...
founded the theory of universal
inductive inference
Inductive reasoning is a method of reasoning in which a general principle is derived from a body of observations. It consists of making broad generalizations based on specific observations. Inductive reasoning is distinct from ''deductive'' re ...
, a theory of prediction based on observations, for example, predicting the next symbol based upon a given series of symbols. This is a formal inductive framework that combines
algorithmic information theory
Algorithmic information theory (AIT) is a branch of theoretical computer science that concerns itself with the relationship between computation and information of computably generated objects (as opposed to stochastically generated), such as st ...
with the Bayesian framework. Universal inductive inference is based on solid philosophical foundations,
and can be considered as a mathematically formalized
Occam's razor
Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...
. Fundamental ingredients of the theory are the concepts of
algorithmic probability In algorithmic information theory, algorithmic probability, also known as Solomonoff probability, is a mathematical method of assigning a prior probability to a given observation. It was invented by Ray Solomonoff in the 1960s.
It is used in induc ...
and
Kolmogorov complexity
In algorithmic information theory (a subfield of computer science and mathematics), the Kolmogorov complexity of an object, such as a piece of text, is the length of a shortest computer program (in a predetermined programming language) that produ ...
.
See also
*
Analogy
Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...
*
Argument
An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialectic ...
*
Argumentation theory
Argumentation theory, or argumentation, is the interdisciplinary study of how conclusions can be supported or undermined by premises through logical reasoning. With historical origins in logic, dialectic, and rhetoric, argumentation theory, includ ...
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Bayesian probability
Bayesian probability is an Probability interpretations, interpretation of the concept of probability, in which, instead of frequentist probability, frequency or propensity probability, propensity of some phenomenon, probability is interpreted as re ...
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Counterinduction
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Explanation
An explanation is a set of Statement (logic), statements usually constructed to description, describe a set of facts which clarifies the causality, causes, wiktionary:context, context, and Logical consequence, consequences of those facts. It may ...
*
Failure mode and effects analysis
Failure mode and effects analysis (FMEA; often written with "failure modes" in plural) is the process of reviewing as many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effe ...
*
Falsifiability
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a sol ...
*
Grammar induction
Grammar induction (or grammatical inference) is the process in machine learning of learning a formal grammar (usually as a collection of ''re-write rules'' or '' productions'' or alternatively as a finite state machine or automaton of some kind) fr ...
*
Inductive logic programming
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Inductive probability
Inductive probability attempts to give the probability of future events based on past events. It is the basis for inductive reasoning, and gives the mathematical basis for learning and the perception of patterns. It is a source of knowledge about ...
*
Inductive programming
Inductive programming (IP) is a special area of automatic programming, covering research from artificial intelligence and programming, which addresses learning of typically declarative (logic or functional) and often recursive programs from inc ...
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Inductive reasoning aptitude
Inductive reasoning aptitude (also called differentiation or inductive learning ability) measures how well a person can identify a pattern within a large amount of data. It involves applying the rules of logic when inferring general principles fr ...
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Inductivism
Inductivism is the traditional and still commonplace philosophy of scientific method to develop scientific theories.James Ladyman, ''Understanding Philosophy of Science'' (London & New York: Routledge, 2002), p5158 Inductivism aims to neutrally o ...
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Inquiry
An inquiry (also spelled as enquiry in British English) is any process that has the aim of augmenting knowledge, resolving doubt, or solving a problem. A theory of inquiry is an account of the various types of inquiry and a treatment of the ...
*
Intuitive statistics Intuitive statistics, or folk statistics, refers to the cognitive phenomenon where organisms use data to make generalizations and predictions about the world. This can be a small amount of sample data or training instances, which in turn contribute ...
*
Lateral thinking
Lateral thinking is a manner of solving problems using an indirect and creative approach via reasoning that is not immediately obvious. It involves ideas that may not be obtainable using only traditional step-by-step logic. The term was first ...
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Laurence Jonathan Cohen
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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 ...
*
Logical reasoning
Two kinds of logical reasoning are often distinguished in addition to formal deduction: induction and abduction. Given a precondition or ''premise'', a conclusion or ''logical consequence'' and a rule or ''material conditional'' that implies the ...
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Logical positivism
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 ...
*
Minimum description length
Minimum Description Length (MDL) is a model selection principle where the shortest description of the data is the best model. MDL methods learn through a data compression perspective and are sometimes described as mathematical applications of Occam ...
*
Minimum message length
Minimum message length (MML) is a Bayesian information-theoretic method for statistical model comparison and selection. It provides a formal information theory restatement of Occam's Razor: even when models are equal in their measure of fit-accurac ...
*
New riddle of induction
The new riddle of induction was presented by Nelson Goodman in ''Fact, Fiction, and Forecast'' as a successor to Hume's original problem. It presents the logical predicates grue and bleen which are unusual due to their time-dependence. Many have ...
*
Open world assumption
In a formal system of logic used for knowledge representation, the open-world assumption is the assumption that the truth value of a statement may be true irrespective of whether or not it is ''known'' to be true. It is the opposite of the clos ...
*
Raven paradox
The raven paradox, also known as Hempel's paradox, Hempel's ravens, or rarely the paradox of indoor ornithology, is a paradox arising from the question of what constitutes evidence for the truth of a statement. Observing objects that are neither ...
*
Recursive Bayesian estimation
In probability theory, statistics, and machine learning, recursive Bayesian estimation, also known as a Bayes filter, is a general probabilistic approach for estimating an unknown probability density function (PDF) recursively over time using inco ...
*
Statistical inference
Statistical inference is the process of using data analysis to infer properties of an underlying probability distribution, distribution of probability.Upton, G., Cook, I. (2008) ''Oxford Dictionary of Statistics'', OUP. . Inferential statistical ...
*
Marcus Hutter
Marcus Hutter (born April 14, 1967 in Munich) is DeepMind Senior Scientist researching the mathematical foundations of artificial general intelligence. He is on leave from his professorship at the ANU College of Engineering and Computer Scie ...
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Stephen Toulmin
References
Further reading
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External links
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''Four Varieties of Inductive Argument''from the Department of Philosophy,
University of North Carolina at Greensboro
The University of North Carolina at Greensboro (UNCG or UNC Greensboro) is a public research university in Greensboro, North Carolina. It is part of the University of North Carolina system. UNCG, like all members of the UNC system, is a stand-al ...
.
* , a psychological review by Evan Heit of the
University of California, Merced
The University of California, Merced (UC Merced) is a public land-grant research university and Hispanic-serving institution located in Merced, California, and is the tenth and newest of the University of California (UC) campuses. Established ...
.
''The Mind, Limber''An article which employs the film
The Big Lebowski
''The Big Lebowski'' () is a 1998 crime comedy film written, produced, and directed by Joel and Ethan Coen. It stars Jeff Bridges as Jeffrey "The Dude" Lebowski, a Los Angeles slacker and avid bowler. He is assaulted as a result of mistaken i ...
to explain the value of inductive reasoning.
The Pragmatic Problem of Induction by Thomas Bullemore
Arguments against Popper's Falsificationism
{{DEFAULTSORT:Inductive Reasoning
Arguments
Causal inference
Concepts in epistemology
Concepts in logic
Concepts in metaphysics
Concepts in the philosophy of science
Critical thinking
Epistemology of science
Intellectual history
Logic
Philosophy of statistics
Problem solving skills
Reasoning