એરિસ્ટોટલ "says that 'on the subject of reasoning' he 'had nothing else on an earlier date to speak of'". However, પ્લેટો reports that syntax was devised before him, by Prodikos of Keos, who was concerned by the correct use of words. Logic seems to have emerged from dialectics; the earlier philosophers made frequent use of concepts like "reductio ad absurdum" in their discussions, but never truly understood the logical implications. Even પ્લેટો had difficulties with તર્કશાસ્ત્ર; although he had a reasonable conception of a deduction system, he could never actually construct one and relied instead on his dialectic. પ્લેટો believed that deduction would simply follow from premises, hence he focused on maintaining solid premises so that the conclusion would logically follow. Consequently, પ્લેટો realized that a method for obtaining conclusions would be most beneficial. He never succeeded in devising such a method, but his best attempt was published in his book "Sophist", where he introduced his division method.

લુપ્ત ગ્રંથો
ઇતીહાસ
Causality, The Four Causes
વકતૃત્વ અને કાવ્ય