Megarian school

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Megara in Attica, lying equidistant from Athens, Thebes, and Corinth Map of Attika.png
Megara in Attica, lying equidistant from Athens, Thebes, and Corinth

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.

Socrates classical Greek Athenian philosopher

Socrates was a classical Greek (Athenian) philosopher credited as one of the founders of Western philosophy, and as being the first moral philosopher of the Western ethical tradition of thought. An enigmatic figure, he made no writings, and is known chiefly through the accounts of classical writers writing after his lifetime, particularly his students Plato and Xenophon. Other sources include the contemporaneous Antisthenes, Aristippus, and Aeschines of Sphettos. Aristophanes, a playwright, is the main contemporary author to have written plays mentioning Socrates during Socrates' lifetime, though a fragment of Ion of Chios' Travel Journal provides important information about Socrates' youth.

Plato describes the "Form of the Good", or more literally "the idea of the good", in his dialogue the Republic (508e2–3), speaking through the character of Socrates. Plato introduces several forms in his works, but identifies the Form of the Good as the superlative. This form is the one that allows a philosopher-in-training to advance to a philosopher-king. It cannot be clearly seen or explained, but once it is recognized, it is the form that allows one to realize all the other forms.

Monism View that attributes oneness or singleness to a concept

Monism attributes oneness or singleness to a concept e.g., existence. Various kinds of monism can be distinguished:



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. [1] 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). [2] It is unlikely, however, that the Megarian school was a genuine institution, nor did it have a unified philosophical position. [3] It was said that the philosophers of the school were first called Megarians and that later they were called Eristics, and then Dialecticians, [4] but it is probable that these names designated splinter groups distinct from the Megarian school. [5] Besides Ichthyas, Euclides' most important pupils were Eubulides of Miletus [6] and Clinomachus of Thurii. [7] It seems to have been under Clinomachus that a separate Dialectical school was founded, [8] which placed great emphasis on logic and dialectic, and Clinomachus was said to have been "the first to write about propositions and predicates." [7] However, Euclides himself taught logic, [9] and his pupil, Eubulides, who was famous for employing celebrated paradoxes, [6] was the teacher of several later dialecticians.

Megara Place in Greece

Megara 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.

Ichthyas, 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.

Stilpo Greek philosopher of the Megarian school

Stilpo 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.

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, [10] 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." [2]

Pyrrho Ancient Greek philosopher

Pyrrho of Elis was a Greek philosopher of Classical antiquity and is credited as being the first Greek skeptic philosopher and founder of Pyrrhonism.

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, 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.

Menedemus of Eretria was a Greek philosopher and founder of the Eretrian school. He learned philosophy first in Athens, and then, with his friend Asclepiades, he subsequently studied under Stilpo and Phaedo of Elis. Nothing survives of his philosophical views apart from a few scattered remarks recorded by later writers.


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," [11] and the opposite of Good was regarded by Euclides as non-existent. [4] 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. [12] 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, [13] and he also rejected Plato's Theory of Forms. [14] In ethics, Stilpo taught freedom, self-control, and self-sufficiency, approaching the teachings of the Cynics, another Socratic school. [15]

The Eleatics were a pre-Socratic school of philosophy founded by Parmenides in the early fifth century BC in the ancient town of Elea. Other members of the school included Zeno of Elea and Melissus of Samos. Xenophanes is sometimes included in the list, though there is some dispute over this. Elea, whose modern-day appellation is Velia, was a Greek colony located in present-day Campania in southern Italy.

Plato Classical Greek philosopher

Plato was an Athenian philosopher during the Classical period in Ancient Greece, founder of the Platonist school of thought, and the Academy, the first institution of higher learning in the Western world.

Ethics branch of philosophy that systematizes, defends, and recommends concepts of right and wrong conduct

Ethics or moral philosophy is a branch of philosophy that involves systematizing, defending, and recommending concepts of right and wrong conduct. The field of ethics, along with aesthetics, concerns matters of value, and thus comprises the branch of philosophy called axiology.

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. [16] 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.

Modal logic is a type of formal logic primarily developed in the 1960s that extends classical propositional and predicate logic to include operators expressing modality. A modal—a word that expresses a modality—qualifies a statement. For example, the statement "John is happy" might be qualified by saying that John is usually happy, in which case the term "usually" is functioning as a modal. The traditional alethic modalities, or modalities of truth, include possibility, necessity, and impossibility. Other modalities that have been formalized in modal logic include temporal modalities, or modalities of time, deontic modalities, epistemic modalities, or modalities of knowledge and doxastic modalities, or modalities of belief.

Material conditional logical connective often symbolized by a forward arrow

The material conditional is a logical connective that is often symbolized by a forward arrow "→". The material conditional is used to form statements of the form p → q which is read as "if p then q". Unlike the English construction "if... then...", the material conditional statement p → q does not conventionally specify a causal relationship between p and q; "p is the cause and q is the consequence from it" is not a generally valid interpretation of p → q. It merely means "if p is true, then q is also true" such that the statement p → q is false only when both p is true and q is false. In a bivalent truth table of p → q, if p is false, then p → q is true regardless of whether q is true or false since (1) p → q is always true as long q is true and (2) p → q is true when both p and q are false. This truth table is useful to prove some mathematical theorems.

Diodorus Cronus 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.

See also

History of logic aspect of history

The history of logic deals with the study of the development of the science of valid inference (logic). Formal logics developed in ancient times in India, China, and Greece. Greek methods, particularly Aristotelian logic as found in the Organon, found wide application and acceptance in Western science and mathematics for millennia. The Stoics, especially Chrysippus, began the development of predicate logic.

Problem of future contingents

Future contingent propositions are statements about states of affairs in the future that are contingent: neither necessarily true nor necessarily false.


  1. Diogenes Laërtius, ii. 47
  2. 1 2 Diogenes Laërtius, ii. 113
  3. Gill & Pellegrin 2006 , p. 132
  4. 1 2 Diogenes Laërtius, ii. 106
  5. O'Toole & Jennings 2004 , p. 406
  6. 1 2 Diogenes Laërtius, ii. 108
  7. 1 2 Diogenes Laërtius, ii. 112
  8. O'Toole & Jennings 2004 , p. 406 Although the name "Dialectical school" was apparently coined by Dionysius of Chalcedon, (Diogenes Laërtius, ii. 106)
  9. Diogenes Laërtius, ii. 107
  10. Diogenes Laërtius, vii. 16
  11. Diogenes Laërtius, ii. 106; Cicero, Academica, ii. 42
  12. Gill & Pellegrin 2006 , p. 134
  13. Aristocles, in Eusebius, Praeparatio Evangelica xiv. 16. 1
  14. Diogenes Laërtius, ii. 119
  15. Goulet-Cazé 1996 , pp. 403–4
  16. Kneale & Kneale 1984 , p. 119

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Euclid of Megara Greek philosopher

Euclid of Megara 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.

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This page is a list of topics in ancient philosophy.

Philo the Dialectician 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.

Nicarete or Nicareta of Megara 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.

Bryson of Achaea was an ancient Greek philosopher.

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Thrasymachus 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.

Dionysius of Chalcedon 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"

Pasicles of Thebes 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 situation of Pasicles teaching Stilpo, Stilpo teaching Crates, and Crates teaching Pasicles. Crates named his son Pasicles.

Stoic logic is the system of propositional logic developed by the Stoic philosophers in ancient Greece. It was one of the two great systems of logic in the classical world. It was largely built and shaped by Chrysippus, the third head of the Stoic school in the 3rd-century BCE. Chrysippus's logic differed from Aristotle's term logic because it was based on the analysis of propositions rather than terms. The smallest unit in Stoic logic is an assertible which is the content of a statement such as "it is day". Assertibles have a truth-value such that at any moment of time they are either true or false. Compound assertibles can be built up from simple ones through the use of logical connectives. The resulting syllogistic was grounded on five basic indemonstrable arguments to which all other syllogisms were claimed to be reducible.