Philo the Dialectician

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For other people named Philo, see Philo (disambiguation).

Philo the Dialectician (fl. 300 BC) was a dialectic philosopher of the Megarian school. He is often called Philo of Megara although the city of his birth is unknown. He is most famous for the disputes he had with his teacher Diodorus Cronus concerning the idea of the possible and the criteria of the truth of conditional statements.


Philo was a disciple of Diodorus Cronus, and a friend of Zeno, though older than the latter.[1] In his Menexenus he mentioned the five daughters of his teacher.[2]

Jerome incorrectly refers to Philo as the teacher of Carneades.[3] Diogenes Laërtius mentions a (presumably different) Philo who was a disciple of Pyrrho.[4]


Philo disputed with Diodorus respecting the idea of the possible and the criteria of the truth of conditional statements.

In regards to things possible, Philo was similar to Aristotle, as he recognized that not only what is, or will be, is possible (as Diodorus maintained), but also what is in itself conformable to the particular purpose of the object in question, as of straw to burn.[5]

Both Philo and Diodorus sought for criteria for the correct form of conditional propositions, and each of them did so in a manner corresponding to what he maintained respecting the idea of the possible. Philo regarded all conditionals as true except those with both a true antecedent and a false consequent; in contrast, Diodorus allowed the validity of conditionals only when the antecedent clause could never lead to an untrue conclusion.[6] A century later, the Stoic philosopher Chrysippus attacked the assumption of each of them.


  1. ^ Diogenes Laërtius, vii. 16: "He [Zeno] used to dispute very carefully with Philo the logician and study along with him. Hence Zeno, who was the junior, had as great an admiration for Philo as his master Diodorus."
  2. ^ Clement of Alexandria, Stromata, iv.
  3. ^ Jerome, Contra Jovinianum, 1
  4. ^ Diogenes Laërtius, ix. 67, 69
  5. ^ Alexander of Aphrodisias, Nat. Qual. i. 14.
  6. ^ Sextus Empiricus, adv. Math. viii. 113, etc. Hypotyp. ii. 110, comp. Cicero, Academica, ii. 47, de Fato, 6.

External links[edit]

 This article incorporates text from a publication now in the public domainSmith, William, ed. (1870). "Philon the Megarian or Dialectician". Dictionary of Greek and Roman Biography and Mythology III. p. 312-313.