Protagoras (/proʊˈtæɡərəs/; Greek: Πρωταγόρας; c. 490 BC – c. 420 BC)[1] was a pre-Socratic Greek philosopher. He is numbered as one of the sophists by Plato. In his dialogue Protagoras, Plato credits him with inventing the role of the professional sophist.

Protagoras also is believed to have created a major controversy during ancient times through his statement that, "Man is the measure of all things", interpreted by Plato to mean that there is no absolute truth but that which individuals deem to be the truth.

Although there is reason to question the extent of the interpretation of his arguments that has followed, that concept of individual relativity was revolutionary for the time, and contrasted with other philosophical doctrines that claimed the universe was based on something objective, outside human influence or perceptions.

Salvator Rosa - Démocrite et Protagoras
Democritus (center) and Protagoras (right)
17th-century painting by Salvator Rosa
in Hermitage Museum
Bornc. 490 BC[1]
Diedc. 420 BC
EraPre-Socratic philosophy
RegionWestern philosophy
Main interests
language, semantics, relativism, rhetoric, agnosticism, ethics
Notable ideas
'Sophist' as teacher for hire, 'Man is the measure of all things'


Protagoras was born in Abdera, Thrace, opposite the island of Thasos (today part of the Xanthi regional unit). According to Aulus Gellius, he originally made his living as a porter, but one day he was seen by the philosopher Democritus carrying a load of small pieces of wood he had tied with a short cord. Democritus realized that Protagoras had tied the load together with such perfect geometric accuracy that he must be a mathematical prodigy. Democritus promptly took him into his own household and taught him philosophy.[2] Protagoras became well known in Athens and even became a friend of Pericles.[3]

The dates of his lifetime are not recorded, but extrapolated from writings that have survived the ages. In Protagoras Plato wrote that, before a gathering of Socrates, Prodicus, and Hippias, Protagoras stated that he was old enough to be the father of any of them. This suggests a birth date of not later than 490 BC. In the Meno he is said to have died at approximately the age of 70, after 40 years as a practicing Sophist.[4] His death, then, may be presumed to have occurred circa 420 BC, but is not known for certain, since assumptions about it are based on an apparently fake story about his trial for impiety in Athens.[5]

Plutarch wrote that Pericles and Protagoras spent a whole day discussing an interesting point of legal responsibility, that probably involved a more philosophical question of causation:[6] "In an athletic contest a man had been accidentally hit and killed with a javelin. Was his death to be attributed to the javelin, to the man who threw it, or to the authorities responsible for the conduct of the games?"[7]


Even though he was mentored by Democritus, Protagoras did not share his enthusiasm for the pursuit of mathematics. "For perceptible lines are not the kind of things the geometer talks about, since no perceptible thing is straight or curved in that way, nor is a circle tangent to a ruler at a point, but the way Protagoras used to say in refuting the geometers" (Aristotles, Metaphysics 997b34-998a4). Protagoras was skeptical about the application of theoretical mathematics to the natural world; he did not believe they were really worth studying at all. According to Philodemus, Protagoras said that "The subject matter is unknowable and the terminology distasteful". Nonetheless, mathematics was considered to be by some a very viable form of art, and Protagoras says on the arts, "art (tekhnê) without practice and practice without art are nothing" (Stobaeus, Selections 3.29.80).

Protagoras also was known as a teacher who addressed subjects connected to virtue and political life. He especially was involved in the question of whether virtue could be taught, a commonplace issue of fifth century BC Greece, that has been related to modern readers through Plato's dialogue. Rather than educators who offered specific, practical training in rhetoric or public speaking, Protagoras attempted to formulate a reasoned understanding, on a very general level, of a wide range of human phenomena, including language and education. In Plato's Protagoras, he claims to teach "the proper management of one's own affairs, how best to run one's household, and the management of public affairs, how to make the most effective contribution to the affairs of the city by word and action".[8]

He also seems to have had an interest in "orthoepeia"—the correct use of words—although this topic is more strongly associated with his fellow sophist Prodicus. In his eponymous Platonic dialogue, Protagoras interprets a poem by Simonides, focusing on the use of words, their literal meaning, and the author's original intent. This type of education would have been useful for the interpretation of laws and other written documents in the Athenian courts.[9] Diogenes Laërtius reports that Protagoras devised a taxonomy of speech acts such as assertion, question, answer, command, etc. Aristotle also says that Protagoras worked on the classification and proper use of grammatical gender.[10]

The titles of his books, such as Technique of Eristics (Technē Eristikōn, literally "Practice of Wranglings"—with wrestling used as a metaphor for intellectual debate), prove that Protagoras also was a teacher of rhetoric and argumentation. Diogenes Laërtius states that he was one of the first to take part in rhetorical contests in the Olympic games.[10]


Protagoras also said that on any matter, there are two arguments (logoi) opposed to one another, and according to Aristotle, Protagoras was criticized for having claimed "to make the weaker argument stronger (ton hēttō logon kreittō poiein)".[10]

Protagoras is credited with the philosophy of relativism, which he discusses in his work, Truth (also known as Refutations).[9][11] Although knowledge of his work is limited, discussion of Protagoras' relativism is based on one of his most famous statements: "Man is the measure of all things: of the things that are, that they are, of the things that are not, that they are not."[12][13] By this, Protagoras meant that each individual is the measure of how things are perceived by that individual. Therefore, things are, or are not, true according to how the individual perceives them. For example, Person X may believe that the weather is cold, whereas Person Y may believe that the weather is hot. According to the philosophy of Protagoras, there is no absolute evaluation of the nature of a temperature because the evaluation will be relative to who is perceiving it. Therefore, to Person X, the weather is cold, whereas to Person Y, the weather is hot. This philosophy implies that there are no absolute "truths". The truth, according to Protagoras, is relative, and differs according to each individual.[9]

As with many fragments of the pre-Socratic philosophers, this phrase has been passed down through the ages, without any context, and consequently, its meaning is open to interpretation. His use of the word χρήματα (chrēmata, "things used") instead of the general word ὄντα (onta, "entities") signifies, however, that Protagoras was referring to things that are used by, or in some way, related to, humans, such as properties, social entities, ideas, feelings, judgments, which originate in the human mind. Protagoras did not suggest that humans must be the measure of the motion of the stars, the growing of plants, or the activity of volcanoes.

As many modern thinkers will, Plato ascribes relativism to Protagoras and uses his predecessor's teachings as a foil for his own commitment to objective and transcendent realities and values. Plato ascribes to Protagoras an early form of what John Wild categorized as phenomenalism.[14] That being an assertion that something that is, or appears for a single individual, is true or real for that individual.

However, as described in Plato's Theaetetus, Protagoras's views allow that some views may result from an ill body or mind. He stressed that although all views may appear equally true, and perhaps, should be equally respected, they certainly are not of equal gravity. One view may be useful and advantageous to the person who has it, while the perception of another may prove harmful. Hence, Protagoras believed that the sophist was there to teach the student how to discriminate between them, i.e., to teach "virtue".

Both Plato and Aristotle argue against some of Protagoras's claims regarding relativity; however, they argue that the concept provides Protagoras with too convenient an exemption from his own theory and that relativism is true for him yet false for those who do not believe it. They claim that by asserting that truth is relative, Protagoras then could say that whatever further theory he proposed must be true.[15]

Because knowledge of most of his work is limited or missing, modern attempts to apply the Protagoras theory of relativism tend to result in disagreement and refer to scientific reasoning. Carol Poster states that with a modern preference toward scientific reasoning and objective truth, for example, rather than considering individuals evaluating their sense of comfort, a modern philosopher would look at a modern instrument, the thermometer, objectively to see the scientific measure of the temperature, whereas the Greek method would entail looking at larger philosophical implications.[16]


Protagoras also was a proponent of agnosticism. Reportedly, in his lost work, On the Gods, he wrote: "Concerning the gods, I have no means of knowing whether they exist or not, nor of what sort they may be, because of the obscurity of the subject, and the brevity of human life."[17][18] According to Diogenes Laërtius, the outspoken, agnostic position taken by Protagoras aroused anger, causing the Athenians to expel him from the city, and all copies of his book were collected and burned in the marketplace. The deliberate destruction of his works also is mentioned by Cicero.[19]

The classicist John Burnet doubts this account, however, as both Diogenes Laërtius and Cicero wrote hundreds of years later and as no such persecution of Protagoras is mentioned by contemporaries who make extensive references to this philosopher.[20] Burnet notes that even if some copies of the Protagoras books were burned, enough of them survived to be known and discussed in the following century. A claim has been made that Protagoras is better classified as an atheist, since he held that if something is not able to be known it does not exist.[21]

Spectrum of topics

Nonetheless, very few fragments from Protagoras have survived, although he is known to have written several different works: Antilogiae and Truth. The latter is cited by Plato, and was known alternatively as, The Throws (a wrestling term referring to the attempt to floor an opponent). It began with the "Man is the measure" (ἄνθρωπος μέτρον) pronouncement. According to Diogenes Laërtius other books by Protagoras include: On the Gods, Art of Eristics, Imperative, On Ambition, On Incorrect Human Actions, On those in Hades, On Sciences, On Virtues, On the Original State of Things and Trial over a Fee.[10]

See also


  1. ^ a b Guthrie, p. 262–263.
  2. ^ Aulus Gellius, Noctes Atticae 5.3.
  3. ^ O'Sullivan, Neil. (1995) "Pericles and Protagoras". Greece & Rome, Vol. 42 (1): 15–23
  4. ^ Plato, Meno, 91e
  5. ^ Filonik, Jakub (2013). "Athenian impiety trials: a reappraisal" (PDF). Dike (16): 36–39. doi:10.13130/1128-8221/4290.
  6. ^ Guthrie, p. 263.
  7. ^ Plutarch, Life of Pericles
  8. ^ Plato, Protagoras, (319a)
  9. ^ a b c Poster, Carol (2005) [2002]. "Protagoras". Internet Encyclopedia of Philosophy. Retrieved 22 October 2013.
  10. ^ a b c d "The Sophists (Stanford Encyclopedia of Philosophy)". Stanford Encyclopedia of Philosophy. Retrieved 2012-05-01.
  11. ^ Mattey, G.J. "Protagoras on Truth". Retrieved 22 October 2013.
  12. ^ Bostock, D (1988). Plato's Theaetetus. Oxford.
  13. ^ This quotation is restated in Plato's Theaetetus at 152a. Sextus Empiricus gives a direct quotation in Adv. math. 7.60: πάντων χρημάτων μέτρον ἐστὶν ἄνθρωπος, τῶν μὲν ὄντων ὡς ἔστιν, τῶν δὲ οὐκ ὄντων ὡς οὐκ ἔστιν. The translation, "Man is the measure ..." has been familiar in English since before the rise of gender-neutral language. In traditional English usage, man referred to hominids. Similarly, in Ancient Greek, Protagoras used the Greek word anthrōpos (human being, person), making a general statement about human beings.
  14. ^ John Wild, "On the Nature and Aims of Phenomenology," Philosophy and Phenomenological Research 3 (1942), p. 88: "Phenomenalism is as old as Protagoras."
  15. ^ Lee, Mi-Kyoung (2005). Epistemology after Protagoras: Responses to relativism in Plato, Aristotle. Oxford: Oxford University Press. ISBN 0-19-926222-5.
  16. ^ Poster, Carol. "Protagoras". Internet Encyclopedia of Philosophy. Retrieved 28 February 2014.
  17. ^ DK 80B4.
  18. ^ The Internet Encyclopedia of Philosophy - Protagoras (c. 490 BCE – c. 420 BCE), Accessed: October 6, 2008. "While the pious might wish to look to the gods to provide absolute moral guidance in the relativistic universe of the Sophistic Enlightenment, that certainty also was cast into doubt by philosophic and sophistic thinkers, who pointed out the absurdity and immorality of the conventional epic accounts of the gods. Protagoras' prose treatise about the gods began "Concerning the gods, I have no means of knowing whether they exist or not or of what sort they may be. Many things prevent knowledge including the obscurity of the subject and the brevity of human life".
  19. ^ Cicero, de Natura Deorum, 1.23.6
  20. ^ John Burnet, "Greek Philosophy: From Thales to Plato", 1914
  21. ^ Tim Whitmarsh, Battling the Gods, Alfred A. Knopf, 2015, pp. 88–89


External links

Aeolic Greek

In linguistics, Aeolic Greek (; also Aeolian , Lesbian or Lesbic dialect) is the set of dialects of Ancient Greek spoken mainly in Boeotia (a region in Central Greece); Thessaly, in the Aegean island of Lesbos; and the Greek colonies of Aeolis in Anatolia and adjoining islands.

The Aeolic dialect shows many archaisms in comparison to the other Ancient Greek dialects (Arcadocypriot, Attic, Ionic, and Doric varieties), as well as many innovations.

Aeolic Greek is widely known as the language of Sappho and of Alcaeus of Mytilene. Aeolic poetry, which is exemplified in the works of Sappho, mostly uses four classical meters known as the Aeolics: Glyconic (the most basic form of Aeolic line), hendecasyllabic verse, Sapphic stanza, and Alcaic stanza (the latter two are respectively named for Sappho and Alcaeus).

In Plato's Protagoras, Prodicus labelled the Aeolic dialect of Pittacus of Mytilene as "barbarian" (barbaros), because of its difference from the Attic literary style: "He didn't know to distinguish the words correctly, being from Lesbos, and having been raised with a barbarian dialect".

Archytas (crater)

Archytas is a lunar impact crater that protrudes into the northern edge of Mare Frigoris. To the northwest is the comparably sized crater Timaeus, and the smaller Protagoras lies in the opposite direction to the southeast. Further to the southwest, beyond the opposite edge of the mare, is the dark-floored crater Plato.

The rim of Archytas is sharp-edged and shows little appearance of erosion due to subsequent impacts. The outer wall is nearly circular, with a slight outward bulge in the southeast. The interior is rough, with a ring of material deposited at the base of the inner wall. Just to the east of the crater midpoint is a pair of central peaks.

The surface surrounding the crater is relatively smooth to the south due to the lava flows that formed the mare. The surface is more rugged to the north and northeast. The satellite crater Archytas B, located to the northwest of Archytas, forms a lava-flooded bay along the edge of the Mare Frigoris.

Cardinal virtues

Four cardinal virtues were recognized in the Bible, Old Testament, classical antiquity and in traditional Christian theology:

Prudence (φρόνησις, phronēsis; Latin: prudentia; also Wisdom, Sophia, sapientia), the ability to discern the appropriate course of action to be taken in a given situation at the appropriate time.

Courage (ἀνδρεία, andreia; Latin: fortitudo): also termed fortitude, forbearance, strength, endurance, and the ability to confront fear, uncertainty, and intimidation

Temperance (σωφροσύνη, sōphrosynē; Latin: temperantia): also known as restraint, the practice of self-control, abstention, discretion, and moderation tempering the appetition. Sōphrosynē can also be translated as sound-mindedness.

Justice (δικαιοσύνη, dikaiosynē; Latin: iustitia): also considered as fairness, the most extensive and most important virtue; the Greek word also having the meaning righteousnessThese principles derive initially from Plato in Republic Book IV, 426–435 (and see Protagoras 330b, which also includes piety (hosiotes)). Cicero expanded on them, and Ambrose, Augustine of Hippo, and Thomas Aquinas adapted them while expanding on the theological virtues.

The term cardinal comes from the Latin cardo (hinge); virtues are so called because they are regarded as the basic virtues required for a virtuous life. They also relate to the Quadrivium.

Ethical subjectivism

Ethical subjectivism is the meta-ethical view which claims that:

Ethical sentences express propositions.

Some such propositions are true.

The truth or falsity of such propositions is ineliminably dependent on the (actual or hypothetical) attitudes of people.This makes ethical subjectivism a form of cognitivism. Ethical subjectivism stands in opposition to moral realism, which claims that moral propositions refer to objective facts, independent of human opinion; to error theory, which denies that any moral propositions are true in any sense; and to non-cognitivism, which denies that moral sentences express propositions at all.The most common forms of ethical subjectivism are also forms of moral relativism, with moral standards held to be relative to each culture or society (c.f. cultural relativism), or even to every individual. The latter view, as put forward by Protagoras, holds that there are as many distinct scales of good and evil as there are subjects in the world. However, there are also universalist forms of subjectivism such as ideal observer theory (which claims that moral propositions are about what attitudes a hypothetical ideal observer would hold). Although divine command theory is considered by some to be a form of ethical subjectivism, defenders of the perspective that divine command theory is not a form of ethical subjectivism say this is based on a misunderstanding: that divine command proponents claim that moral propositions are about what attitudes God holds, but this understanding is deemed incorrect by some, such as Robert Adams who claims that divine command theory is concerned with whether a moral command is or isn't "contrary to the commands of (a loving) God".

Know thyself

The Ancient Greek aphorism "know thyself" (Greek: γνῶθι σεαυτόν, transliterated: gnōthi seauton; also ... σαυτόν … sauton with the ε contracted), is one of the Delphic maxims and was inscribed in the pronaos (forecourt) of the Temple of Apollo at Delphi according to the Greek writer Pausanias (10.24.1). The phrase was later expounded upon by the philosopher Socrates who taught that:

The unexamined life is not worth living.

In Latin the phrase, "know thyself," is given as nosce te ipsum or temet nosce.The maxim, or aphorism, "know thyself" has had a variety of meanings attributed to it in literature.

Laconic phrase

A laconic phrase or laconism is a concise or terse statement, especially a blunt and elliptical rejoinder. It is named after Laconia, the region of Greece including the city of Sparta, whose ancient inhabitants had a reputation for verbal austerity and were famous for their blunt and often pithy remarks.

Law of noncontradiction

In logic, the law of non-contradiction (LNC) (also known as the law of contradiction, principle of non-contradiction (PNC), or the principle of contradiction) states that contradictory propositions cannot both be true, e. g. the two propositions "A is B" and "A is not B" are mutually exclusive. Formally this is expressed as the tautology ~(p & ~p).

One reason to have this law is the principle of explosion, which states that anything follows from a contradiction. The law is employed in a reductio ad absurdum proof.

To express the fact that the law is tenseless and to avoid equivocation, sometimes the law is amended to say "contradictory propositions cannot both be true 'at the same time and in the same sense'".

It is one of the so called three laws of thought, along with its complement, the law of excluded middle, and the law of identity. The law of noncontradiction is logically equivalent to the law of excluded middle by De Morgan's laws. However, no system of logic is built on just these laws, and none of these laws provide inference rules, such as modus ponens or De Morgan's laws.

The law of non contradiction and the law of excluded middle create a dichotomy in "logical space", wherein the two parts are "mutually exclusive" and "jointly exhaustive". The law of non-contradiction is merely an expression of the mutually exclusive aspect of that dichotomy, and the law of excluded middle, an expression of its jointly exhaustive aspect.

List of speakers in Plato's dialogues

The following is a list of the speakers found in the dialogues traditionally ascribed to Plato, including extensively quoted, indirect and conjured speakers. Dialogues, as well as Platonic Epistles and Epigrams, in which these individuals appear dramatically but do not speak are listed separately.

Unnamed speakers

Lycophron (sophist)

Lycophron (; Greek: Λυκόφρων) was a sophist of Ancient Greece.

The central point about Lycrophron as attacked in the Politics of Aristotle, is that Lycrophron rejected the idea that the state exists to make people "just and good", instead holding the view that justice and law is about preventing people violating the bodies and goods of each other. This is the only reference to Lycrophron in the Politics.

The details of his life remain obscure, other than a number of references in the works of Aristotle. Lycophron was probably among the students of Gorgias, and is mentioned as a sophist by Aristotle. He rejected the supposed value of an aristocratic birth, claiming that Now the nobility of good birth is obscure, and its grandeur a matter of words.

meaning that there is no factual difference between those well-born and those low-born; only words and opinion assign value to these different circumstances of birth. This statement may indicate that Lycophron shared the beliefs of Antiphon, that (regardless of their ancestry) both Greeks and barbarians are born with the same capacities: An egalitarian belief that was a minority view in the 5th century BC. He is also known for his statement (reproduced by Aristotle, in the latter's Politics, 1280b10), that "law is only a convention, a surety to another of justice". Also translated as "a guarantor of men's rights against one another". He thus believed that law is a matter of agreement, a social convention and not a natural or universal standard (there is no evidence that Lycophron rejected the idea that law is a universal standard - indeed his view appears far more universalist than that of Aristotle, in that Lycophron proposes a single standard, what would now be called the non aggression principle, in relation to all states). In this respect his views on law are similar to those of Protagoras. This means that he treats law as a mere means, in the context of a (perhaps primitive) social contract theory, without considering it as something special, in contradistinction to, e.g., Plato but similar to both Thrasymachus and Callicles, albeit that their theories have – as far as can be ascertained from the information available about them – more specific characteristics.While Lycophron is considered one of the first proponents of a social contract theory, this is mostly a conjecture based on his theory of law. His few surviving quotes do not include a theory on the emergence of society from agreements. Such ideas did exist, however, in the works of his contemporary Protagoras. These 5th-century BC ideas viewed society and morality as human creations, both aiming to protect the lives and safety of the community members. The laws were subject to change, reflecting the changing views of a society. There was no "unchanging standard of righteousness". In other words, Protagoras and like-minded thinkers were precursors of Utilitarianism.In Metaphysics, Lycophron is quotted as claiming that "knowledge is a communion of knowledge and of soul". And also that the communion is the cause of the unity of knowledge and the soul. In Physics, it is mentioned that when Lycophron discussed "whether the part and the whole are one or more than one" he avoided using the singular form of the verb "to be". In Rhetoric, Aristotle examines several peculiar expressions used by Lycophron, such as "the many-visaged sky of the mighty-peaked earth", "the narrow-passaged promontory", calling Xerxes "a monster of a man" and Sciron "a human destroyer". The same work includes another reference to a Lycophron, though it fits poorly with what is known of the sophist. Aristotle reports that an opponent of Lycophron and Peitholaus stated in a law-court that "These men used to sell you when they are at home, and now they have come here and bought you." There is no context given to this phrase, though modern scholars suspect this is a reference to a case involving Lycophron I of Pherae, a tyrant.In Sophistical Refutations, Aristotle mentions Lycophron as an example of changing the subject of a conversation when one has nothing to state on the original subject. He reports that once Lycophron was compelled by certain persons to speak in praise of the lyre. He reportedly found himself at a loss for words on this subject. So he offered a few words on the musical organ and then switched the topic to Lyra, the constellation named after it. Being more knowledgeable in this topic, he had much more to say.


Meno (; Greek: Μένων, Menōn) is a Socratic dialogue written by Plato. It appears to attempt to determine the definition of virtue, or arete, meaning virtue in general, rather than particular virtues, such as justice or temperance. The first part of the work is written in the Socratic dialectical style and Meno is reduced to confusion or aporia. In response to Meno's paradox (or the learner's paradox), however, Socrates introduces positive ideas: the immortality of the soul, the theory of knowledge as recollection (anamnesis), which Socrates demonstrates by posing a mathematical puzzle to one of Meno's slaves, the method of hypothesis, and, in the final lines, the distinction between knowledge and true belief.


Orthoepy is the study of pronunciation of a particular language, within a specific oral tradition. The term is from the Greek ὀρθοέπεια, from ὀρθός orthos ("correct") and ἔπος epos ("speech"). The antonym is cacoepy "bad or wrong pronunciation". The pronunciation of the word orthoepy itself varies widely; the OED recognizes the variants /ˈɔːθəʊˌiːpi/, /ˈɔːθəʊˌɛpi/, /ˈɔːθəʊɨpi/, and /ɔːˈθəʊɨpi/ for British English, as well as /ɔrˈθoʊəpi/ for American English.

The tetrasyllabic pronunciation is sometimes indicated with a diaeresis: orthoëpy, such as in the title of Edward Barrett Warman's Warman's Practical Orthoëpy and Critique, published in 1888 and found in Google Books.

Warman states on page 5: "Words possess three special characteristics: They have their Eye-life - Orthography; Ear-life - Orthoëpy; Soul-life - Significance." As with Warman's book, the purpose of this article is "to deal exclusively with the ear-life, or orthoëpy.


In the culture of ancient Greece, the term paideia (also spelled paedeia) (; Greek: παιδεία, paideía) referred to the rearing and education of the ideal member of the polis. It incorporated both practical, subject-based schooling and a focus upon the socialization of individuals within the aristocratic order of the polis. The practical aspects of this education included subjects subsumed under the modern designation of the liberal arts (rhetoric, grammar, and philosophy are examples), as well as scientific disciplines like arithmetic and medicine. An ideal and successful member of the polis would possess intellectual, moral and physical refinement, so training in gymnastics and wrestling was valued for its effect on the body alongside the moral education which the Greeks believed was imparted by the study of music, poetry, and philosophy. This approach to the rearing of a well-rounded Greek male was common to the Greek-speaking world, with the exception of Sparta where a rigid and militaristic form of education known as the agoge was practiced.

Paradox of the Court

The Paradox of the Court, also known as the counterdilemma of Euathlus, is a very old problem in logic stemming from ancient Greece. It is said that the famous sophist Protagoras took on a pupil, Euathlus, on the understanding that the student pay Protagoras for his instruction after he wins his first court case. After instruction, Euathlus decided to not enter the profession of law, and Protagoras decided to sue Euathlus for the amount owed.Protagoras argued that if he won the case he would be paid his money. If Euathlus won the case, Protagoras would still be paid according to the original contract, because Euathlus would have won his first case.

Euathlus, however, claimed that if he won, then by the court's decision he would not have to pay Protagoras. If, on the other hand, Protagoras won, then Euathlus would still not have won a case and would therefore not be obliged to pay.

The question is: which of the two men is in the right?

The story is related by the Latin author Aulus Gellius in Attic Nights.


Peritrope (Greek: περιτροπή) is Socrates' argument against Protagoras' view of relative truth, as presented in Plato's book known as Theaetetus (169–171e). This formed part of the former's eighth objection, the "table-turning" argument that maintained Protagoras' doctrine was self-refuting.

Protagoras (crater)

Protagoras is a lunar impact crater that is located on the Mare Frigoris in the northern part of the Moon. To the north-northwest is the slightly larger crater Archytas, and to the southeast is the prominent Aristoteles.

The rim of Protagoras is circular and rises above the surrounding flat terrain, although the rim dips down along the southwestern edge. The interior floor contains a few light markings but no formations of interest. There is an area of rough terrain just to the east of this crater, but the surroundings are otherwise level with only a few small craters in the vicinity.

The crater is named for the Greek sophist Protagoras of Abdera.

Protagoras (dialogue)

Protagoras (; Greek: Πρωταγόρας) is a dialogue by Plato. The traditional subtitle (which may or may not be Plato's) is "or the Sophists". The main argument is between the elderly Protagoras, a celebrated Sophist, and Socrates. The discussion takes place at the home of Callias, who is host to Protagoras while he is in town, and concerns the nature of Sophists, the unity and the teachability of virtue. A total of twenty-one people are named as present.

Seven Sages of Greece

The Seven Sages (of Greece) or Seven Wise Men (Greek: οἱ ἑπτὰ σοφοί hoi hepta sophoi) was the title given by classical Greek tradition to seven philosophers, statesmen, and law-givers of the 6th century BC who were renowned for their wisdom.


A sophist (Greek: σοφιστής, sophistes) was a specific kind of teacher in ancient Greece, in the fifth and fourth centuries BC. Many sophists specialized in using the tools of philosophy and rhetoric, though other sophists taught subjects such as music, athletics, and mathematics. In general, they claimed to teach arete ("excellence" or "virtue", applied to various subject areas), predominantly to young statesmen and nobility.

The term originated from Greek σόφισμα, sophisma, from σοφίζω, sophizo "I am wise"; confer σοφιστής, sophistēs, meaning "wise-ist, one who does wisdom," and σοφός, sophós means "wise man".

Theaetetus (dialogue)

The Theaetetus (; Greek: Θεαίτητος) is one of Plato's dialogues concerning the nature of knowledge, written circa 369 BCE.

In this dialogue, Socrates and Theaetetus discuss three definitions of knowledge: knowledge as nothing but perception, knowledge as true judgment, and, finally, knowledge as a true judgment with an account. Each of these definitions is shown to be unsatisfactory.

Socrates declares Theaetetus will have benefited from discovering what he does not know, and that he may be better able to approach the topic in the future. The conversation ends with Socrates' announcement that he has to go to court to face a criminal indictment.

Sophists of the 5th century BC

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