"To summarize these fragments of the early philosophers, we may say that in general they illustrate conventional morality of conduct as regards friendship, self-control in anger, and avoidance of evil-speaking and slander. A theory of the laughable is not definitely formulated, but there are suggestions which later find an important place in the theory, such as the necessity of relaxation and laughter as a preparation for serious pursuits, avoidance of excess in laughter, condemnation of laughter directed at the unfortunate, necessity for the reformer to be free from serious faults himself."From Lane Cooper's An Aritotelian Theory of Comedy (NY: Hartcourt, Brace and Co., 1922), p. 99. (Citing the doctoral dissertation of Mary A. Grant, "The Ancient Rhetorical Theories of the Laughable in Cicero and Horace")
Pre-Socratics on Comedy
Though pre-Socratic philosophers wrote little about comedy, their observations were brought forward by Plato and Aristotle.