Radical skepticism (or radical scepticism in

British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...

) is the

philosophical position A philosophical movement refers to the phenomenon defined by a group of philosophers who share an origin or style of thought. Their ideas may develop substantially from a process of learning and communication within the group, rather than from out ...

that

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 ...

is most likely impossible. Radical skeptics hold that doubt exists as to the veracity of every

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 that certainty is therefore never justified. To determine the extent to which it is possible to respond to radical skeptical challenges is the task of

epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...

or "the theory of knowledge". Several

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 ...

, including

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 ...

Cratylus Cratylus ( ; grc, Κρατύλος, ''Kratylos'') was an ancient Athenian philosopher from the mid-late 5th century BCE, known mostly through his portrayal in Plato's dialogue '' Cratylus''. He was a radical proponent of Heraclitean philosophy ...

, Pyrrho,

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 Acad ...

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 beg ...

, Aenesidemus,

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 est ...

, and

Sextus Empiricus Sextus Empiricus ( grc-gre, Σέξτος Ἐμπειρικός, ; ) was a Greek Pyrrhonist philosopher and Empiric school physician. His philosophical works are the most complete surviving account of ancient Greek and Roman Pyrrhonism, and bec ...

have been viewed as having expounded radically skeptic positions. Three of the Hellenistic philosophies held radically skeptic views:

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 ...

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 indi ...

, and Cyrenaicism. In ancient Greek the radical skeptical view was termed ''

acatalepsy In philosophy, acatalepsy (from the Greek ἀκαταληψία "inability to comprehend" from alpha privative and καταλαμβάνειν, "to seize") is incomprehensibleness, or the impossibility of comprehending or conceiving a thing. It ...

,'' denoting the ungraspablity of knowledge. In modern philosophy, two representatives of radical skepticism are

Michel de Montaigne Michel Eyquem, Sieur de Montaigne ( ; ; 28 February 1533 – 13 September 1592), also known as the Lord of Montaigne, was one of the most significant philosophers of the French Renaissance. He is known for popularizing the essay as a liter ...

(most famously known for his skeptical remark, ''Que sçay-je ?'', 'What do I know?' in Middle French; modern French ''Que sais-je'' ?) and

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 ...

(particularly as set out in ''

A Treatise of Human Nature '' A Treatise of Human Nature: Being an Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects'' (1739–40) is a book by Scottish philosopher David Hume, considered by many to be Hume's most important work and one of the ...

'', Book 1: "Of the Understanding"). As radical skepticism can be used as an objection for most or all beliefs, many philosophers have attempted to refute it. For example,

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, ...

wrote "Skepticism, while logically impeccable, is psychologically impossible, and there is an element of frivolous insincerity in any philosophy which pretends to accept it." One attempt at a counter-argument by J.A.J. Peters goes that radical skepticism should either be in doubt of itself, or affirm itself. But affirming skepticism is a contradiction, hence skepticism cannot be maintained according to this argument. .A.J. Peters- (Metaphysica (1959) second ed. 1967 pgs. 42-45)

References

Leavitt, Fred (2021) If Ignorance is Bliss We Should All be Ecstatic. Open Books ;Notes
The Epistemology Page
{{DEFAULTSORT:Radical Skepticism Skepticism Pyrrhonism

See also

References