Panthoides was a dialectician

Dialectician

A dialectician is a philosopher who views the world in terms of complementary opposites and the interactions thereof. In popular usage, the central feature of dialectic is the concept of "thesis, antithesis, synthesis" - when an idea or phenomenon arises, it carries within itself the seed of its...

 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

Lyco of Troas

Lyco of Troas, son of Astyanax, was a Peripatetic philosopher and the disciple of Strato, whom he succeeded as the head of the Peripatetic school, c. 269 BC; and he held that post for more than forty-four years.-Life:...

. He wrote a book called On Ambiguities, against which the Stoic

STOIC

STOIC was a variant of Forth.It started out at the MIT and Harvard Biomedical Engineering Centre in Boston, and was written in the mid 1970s by Jonathan Sachs...

 philosopher Chrysippus

Chrysippus

Chrysippus of Soli was a Greek Stoic philosopher. He was a native of Soli, Cilicia, but moved to Athens as a young man, where he became a pupil of Cleanthes in the Stoic school. When Cleanthes died, around 230 BC, Chrysippus became the third head of the school...

 wrote a treatise.

He disagreed with Diodorus Cronus

Diodorus Cronus

Diodorus Cronus was a Greek philosopher and dialectician connected to the Megarian school. He was most notable for logic innovations, including his master argument fomulated in response to Aristotle's discussion of future contingents.-Life:...

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.