Dionysius of Chalcedon (Greek: Διονύσιος; fl. 320 BC)[1] was a Greek philosopher and dialectician connected with the Megarian school. He was a native of Chalcedon on the coast of Bithynia.[2] 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".[3] One area of activity for the dialecticians was the framing of definitions,[4] and Aristotle criticises a definition of life by Dionysius in his Topics:[5]

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.[6]


  1. ^ Dorandi 1999, p. 47.
  2. ^ Laërtius 1925, § 106; Strabo, xii. 4. 9
  3. ^ Laërtius 1925, § 106.
  4. ^ Craig 1998.
  5. ^ Aristotle, Topics vi. 10
  6. ^ Laërtius 1925, § 98.