The Megarian school of philosophy, which flourished in the 4th century BC, was founded by Euclides of Megara, one of the pupils of Socrates. Its ethical teachings were derived from Socrates, recognizing a single good, which was apparently combined with the Eleatic doctrine of Unity. Some of Euclides' successors developed logic to such an extent that they became a separate school, known as the Dialectical school. Their work on modal logic, logical conditionals, and propositional logic played an important role in the development of logic in antiquity.
The Megarian school of philosophy was founded by Euclides of Megara, who had been one of the pupils of Socrates in the late 5th century BC. His successors, as head of the school in Megara, were said to have been Ichthyas (mid 4th century BC), and Stilpo (late 4th century BC). It is unlikely, however, that the Megarian school was a genuine institution, nor did it have a unified philosophical position. It was said that the philosophers of the school were first called Megarians and that later they were called Eristics, and then Dialecticians, but it is probable that these names designated splinter groups distinct from the Megarian school. Besides Ichthyas, Euclides' most important pupils were Eubulides of Miletus and Clinomachus of Thurii. It seems to have been under Clinomachus that a separate Dialectical school was founded, which placed great emphasis on logic and dialectic, and Clinomachus was said to have been "the first to write about propositions and predicates." However, Euclides himself taught logic, and his pupil, Eubulides, who was famous for employing celebrated paradoxes, was the teacher of several later dialecticians.
Via Stilpo, the Megarian school is said to have influenced Pyrrho, the Eretrian school under Menedemus and Asclepiades, and Zeno, the founder of Stoicism. Zeno was said to have studied under Stilpo and Diodorus Cronus, and to have disputed with Philo the Dialectician. It was perhaps the Dialecticians, Diodorus and Philo, who were the biggest influence on the development of Stoic logic, and that Zeno studied under Stilpo to learn his moral teachings, although Stilpo, too, is said to have excelled "in the invention of arguments and in sophistry."
Euclides had been a pupil of Socrates, but ancient historians regarded him as a successor to the Eleatics, hence his philosophy was seen as a fusion of Eleatic and Socratic thought. Thus the Eleatic idea of "The One" was identified with the Socratic "Form of the Good," and the opposite of Good was regarded by Euclides as non-existent. But the emphasis of his thought is not on being but on the good, and idea that what is opposite to the good does not exist arises from the understanding of the good's unity. This theme is typically Socratic, what matters is the moral good and the will of the good person to strive towards it. Stilpo is said to have continued the Eleatic tendency, by asserting a strict monism and denying all change and motion, and he also rejected Plato's Theory of Forms. In ethics, Stilpo taught freedom, self-control, and self-sufficiency, approaching the teachings of the Cynics, another Socratic school.
Besides studying logical puzzles and paradoxes, the Dialecticians made two important logical innovations, by re-examining modal logic, and by starting an important debate on the nature of conditional statements. This was the work of Diodorus Cronus and Philo the Dialectician, the only two members of the Dialectical school we have detailed information about. Through their development of propositional logic, the Dialectical school played an important role in the development of logic, which was an important precursor of Stoic logic.
Alexinus (; Greek: Ἀλεξῖνος; c. 339–265 BC) of Elis, was a philosopher of Megarian school and a disciple of Eubulides. From his argumentative nature he was facetiously named the wrangler (Greek: Ἐλεγξῖνος), From Elis he went to Olympia, hoping to found a sect which was to be called the Olympian, but his disciples soon became disgusted with the unhealthiness of the place and their scanty means of subsistence, and left him with a single attendant.
None of his doctrines have been preserved, but from the brief mention made of him by Cicero, he seems to have dealt in logical puzzles. Athenaeus mentions a paean which he wrote in honour of Craterus, the Macedonian, and which was sung at Delphi to the sound of the lyre. Alexinus also wrote against Zeno, and against Ephorus the historian. Diogenes Laërtius has preserved some lines on his death which was caused by his being pierced with a reed while swimming in the Alpheus.In 267-6, Alexinus debated rhetorical questions with Hermarchus the Epicurean. Philodemus in his On Rhetoric quotes a rebuttal by Hermarchus in which he cites Alexinus. Alexinus criticizes the rhetorical sophists for wasting their time on investigation of useless subjects, such as diction, memory, and the interpretation of obscure passages in the poets.Apollonius Cronus
Apollonius Cronus (Greek: Ἀπολλώνιος Κρόνος; fl. 4th century BCE) from Cyrene was a philosopher of the Megarian school.
Very little is known about him. He was the pupil of Eubulides, and was the teacher of Diodorus Cronus, as Strabo relates:
Apollonius Cronus, was from Cyrene, ... being the teacher of Diodorus the Dialectician, who also was given the appellation "Cronus," certain persons having transferred the epithet of the teacher to the pupil.
The epithet "Cronus" roughly translates as "old fogey".Bryson of Achaea
Bryson of Achaea (or Bryson the Achaean; Greek: Βρύσων ὁ Ἀχαιός, gen.: Βρύσωνος; fl. 330 BC) was an ancient Greek philosopher.
Very little information is known about him. He was said to have been a pupil of Stilpo and Clinomachus, which would mean that he was a philosopher of the Megarian school. He was said to have taught Crates the Cynic, Pyrrho the Skeptic, and Theodorus the Atheist. Diogenes Laërtius includes him among a list of philosophers who left no writings.He is probably not the same person as Bryson of Heraclea, the sophist and mathematician who seems to have lived in the time of Socrates. The Suda, in its entry on Socrates, may be confusing the two Brysons when it refers to Bryson of Heraclea:
Bryson of Heraclea introduced eristic dialectic after Euclides, whereas Clinomachus augmented it, and whereas many came on account of it, it came to an end with Zeno of Citium, for he gave it the name Stoic, after its location, this having occurred in the 105th Olympiad; but some [say that] Bryson was a student not of Socrates but of EuclidesDiodorus Cronus
Diodorus Cronus (Greek: Διόδωρος Κρόνος; died c. 284 BC) was a Greek philosopher and dialectician connected to the Megarian school. He was most notable for logic innovations, including his master argument formulated in response to Aristotle's discussion of future contingents.Dionysius of Chalcedon
Dionysius of Chalcedon (Greek: Διονύσιος; fl. 320 BC) was a Greek philosopher and dialectician connected with the Megarian school. He was a native of Chalcedon on the coast of Bithynia. Dionysius was the person who first used the name Dialecticians to describe a splinter group within the Megarian school "because they put their arguments into the form of question and answer". One area of activity for the dialecticians was the framing of definitions, and Aristotle criticises a definition of life by Dionysius in his Topics:
This is, moreover, what happens to Dionysius' definition of "life" when stated as "a movement of a creature sustained by nutriment, congenitally present with it"
Dionysius is also reported to have taught Theodorus the Atheist.Eretrian school
The Eretrian school of philosophy was originally the School of Elis where it had been founded by Phaedo of Elis; it was later transferred to Eretria by his pupil Menedemus. It can be referred to as the Elian–Eretrian School, on the assumption that the views of the two schools were similar. It died out after the time of Menedemus (3rd century BC), and, consequently, very little is known about its tenets. Phaedo had been a pupil of Socrates, and Plato named a dialogue, Phaedo, in his honor, but it is not possible to infer his doctrines from the dialogue. Menedemus was a pupil of Stilpo at Megara before becoming a pupil of Phaedo; in later times, the views of his school were often linked with those of the Megarian school. Menedemus' friend and colleague in the Eretrian school was Asclepiades of Phlius.
Like the Megarians they seem to have believed in the individuality of "the Good," the denial of the plurality of virtue, and of any real difference existing between the Good and the True. Cicero tells us that they placed all good in the mind, and in that acuteness of mind by which the truth is discerned. They denied that truth could be inferred by negative categorical propositions, and would only allow positive ones, and of these only simple ones.Eubulides
Eubulides (Greek: Εὑβουλίδης; fl. 4th century BCE) of Miletus was a philosopher of the Megarian school, and a pupil of Euclid of Megara. He is famous for his paradoxes.Euclid of Megara
Euclid of Megara (; also Euclides, Eucleides; Greek: Εὐκλείδης ὁ Μεγαρεύς; c. 435 – c. 365 BC) was a Greek Socratic philosopher who founded the Megarian school of philosophy. He was a pupil of Socrates in the late 5th century BC, and was present at his death. He held the supreme good to be one, eternal and unchangeable, and denied the existence of anything contrary to the good. Editors and translators in the Middle Ages often confused him with Euclid of Alexandria when discussing the latter's Elements.Euphantus
Euphantus (Greek: Εὔφαντος; fl. c. 320 BCE) of Olynthus was a philosopher of the Megarian school as well as an historian and tragic poet. He was the disciple of Eubulides of Miletus, and the instructor of Antigonus II Gonatas king of Macedonia. He wrote many tragedies, which were well received at the games. He also wrote a very highly esteemed work, On Kingship (Greek: Περὶ Βασιλείας), addressed to Antigonus, and a history of his own times. He lived to a great age.Athenaeus refers to Euphantus relating a detail about Ptolemy III Euergetes of Egypt who reigned much later. The discrepancy has been explained variously, by supposing the existence of an Egyptian Euphantus, or by amending "III" to "I".Ichthyas
Ichthyas (Greek: Ἰχθύας; fl. 4th-century BCE), the son of Metallus, was a Greek philosopher and a disciple and successor of Euclid of Megara in the Megarian school. He was a colleague of Thrasymachus of Corinth in the school. Ichthyas is described as a man of great eminence, and Diogenes of Sinope is said to have addressed a dialogue to him.According to Hilarius Emonds, correcting a previously misread passage in Tertullian's Apologeticus, Ichthyas was a leader in the oligarchic revolt in Megara in 375 BCE.Megara
Megara (; Greek: Μέγαρα, pronounced [ˈmeɣara]) is a historic town and a municipality in West Attica, Greece. It lies in the northern section of the Isthmus of Corinth opposite the island of Salamis, which belonged to Megara in archaic times, before being taken by Athens. Megara was one of the four districts of Attica, embodied in the four mythic sons of King Pandion II, of whom Nisos was the ruler of Megara. Megara was also a trade port, its people using their ships and wealth as a way to gain leverage on armies of neighboring poleis. Megara specialized in the exportation of wool and other animal products including livestock such as horses. It possessed two harbors, Pegae, to the west on the Corinthian Gulf and Nisaea, to the east on the Saronic Gulf of the Aegean Sea.Nicarete of Megara
Nicarete or Nicareta of Megara (Greek: Νικαρέτη, Nikarétē) was a philosopher of the Megarian school who flourished around 300 BC. She is stated by Athenaeus to have been a hetaera of good family and education, and to have been a disciple of Stilpo. Diogenes Laërtius states that she was Stilpo's mistress, though he had a wife.Panthoides
Panthoides (Greek: Πανθοίδης; fl. c. 275 BCE) was a dialectician and philosopher of the Megarian school. He concerned himself with "the logical part of philosophy", and at some point taught the Peripatetic philosopher Lyco of Troas. He wrote a book called On Ambiguities, against which the Stoic philosopher Chrysippus wrote a treatise.He disagreed with Diodorus Cronus concerning his Master Argument, arguing that something is possible which can never be true, and that the impossible can never be the consequence of the possible, and that therefore not everything that has happened is necessarily true. Diodorus' view was that everything that has happened must be true, and that therefore nothing is possible which can never be true.Pasicles of Thebes
Pasicles of Thebes (Greek: Πασικλῆς ὁ Θηβαῖος; 4th century BC) was a Greek philosopher and brother of the Cynic philosopher Crates of Thebes. He attended the lectures of his brother Crates, but he is otherwise connected with the Megarian school of philosophy, because Diogenes Laërtius calls him a pupil of Euclid of Megara, and the Suda calls him a pupil of an unknown "Dioclides the Megarian." Pasicles is said to have been the teacher of Stilpo, who became leader of the Megarian school. Thus we have the implausible (although not impossible) situation of Pasicles teaching Stilpo, Stilpo teaching Crates, and Crates teaching Pasicles. Crates named his son Pasicles.Philo the Dialectician
Philo the Dialectician (Greek: Φίλων; fl. 300 BC) was a dialectic philosopher of the Megarian school. He is sometimes called Philo of Megara although the city of his birth is unknown. He is most famous for the debate he had with his teacher Diodorus Cronus concerning the idea of the possible and the criteria of the truth of conditional statements.Problem of future contingents
Future contingent propositions (or simply, future contingents) are statements about states of affairs in the future that are contingent: neither necessarily true nor necessarily false.
The problem of future contingents seems to have been first discussed by Aristotle in chapter 9 of his On Interpretation (De Interpretatione), using the famous sea-battle example. Roughly a generation later, Diodorus Cronus from the Megarian school of philosophy stated a version of the problem in his notorious master argument. The problem was later discussed by Leibniz.
The problem can be expressed as follows. Suppose that a sea-battle will not be fought tomorrow. Then it was also true yesterday (and the week before, and last year) that it will not be fought, since any true statement about what will be the case in the future was also true in the past. But all past truths are now necessary truths; therefore it is now necessarily true in the past, prior and up to the original statement "A sea battle will not be fought tomorrow", that the battle will not be fought, and thus the statement that it will be fought is necessarily false. Therefore, it is not possible that the battle will be fought. In general, if something will not be the case, it is not possible for it to be the case. "For a man may predict an event ten thousand years beforehand, and another may predict the reverse; that which was truly predicted at the moment in the past will of necessity take place in the fullness of time" (De Int. 18b35).
This conflicts with the idea of our own free choice: that we have the power to determine or control the course of events in the future, which seems impossible if what happens, or does not happen, is necessarily going to happen, or not happen. As Aristotle says, if so there would be no need "to deliberate or to take trouble, on the supposition that if we should adopt a certain course, a certain result would follow, while, if we did not, the result would not follow".Stilpo
Stilpo (or Stilpon; Greek: Στίλπων, gen.: Στίλπωνος; c. 360 – c. 280 BC) was a Greek philosopher of the Megarian school. He was a contemporary of Theophrastus, Diodorus Cronus, and Crates of Thebes. None of his writings survive, he was interested in logic and dialectic, and he argued that the universal is fundamentally separated from the individual and concrete. His ethical teachings approached that of the Cynics and Stoics. His most important followers were Pyrrho, the founder of Pyrrhonism, and Zeno of Citium, the founder of Stoicism.Thrasymachus of Corinth
Thrasymachus (Greek: Θρασύμαχος; fl. 4th century BCE) of Corinth, was a philosopher of the Megarian school. Little is known about him except that he was colleague and friend of Ichthyas, and he had presumably been taught by Euclid of Megara, the founder of the school. He was said to have been the teacher of Stilpo.