Marcus Tullius Cicero (106–43 b.c.), a lawyer, orator, statesman, and philosopher, was likely the greatest intellect of the ancient Roman republic. He is usually called a “Stoic,” after the group of postclassical philosophers who carried on their disputations while taking their ease under the stoa, or porticos, of Athens. Cicero calls himself such, but questions have been raised as to whether he fit in with the other Stoics or departed from them by way of a return to stricter adherence to the philosophic principles of the classical thinkers Socrates, Plato, and Aristotle. These three are, of course, the three great figures of political philosophy at its beginnings. Aristotle (384–322 b.c.), the last of the three, wrote treatises. A treatise is a work that endeavors to offer demonstrative proofs regarding the matters treated. He seems to have meant this method as an improvement on the work of his teacher, Plato (427–347 b.c.). All of Plato's writings that have come down to us (other than a few letters) are called “dialogues.” The dialogues look a bit like plays and they have something of the poetic quality of plays. Plato was the first political philosopher to leave behind a body of writings. He was the most prominent follower of Socrates (469–399 b.c.), who left no writings. The oldest academic joke explains that Socrates “didn't get tenure” because he didn't publish anything. Cicero was the first to say that Socrates founded political philosophy. He wrote:

What we know of Socrates we learn from the writings of his contemporaries – his close associate, Xenophon, and the comic poet, Aristophanes, as well as his greatest adherent, Plato, and, once removed, Plato's pupil, Aristotle. We can begin to see the origin of political philosophy by reading the Aristophanes comedy the Clouds; the Platonic dialogue that preserves for us the defense speech of Socrates at the trial that ended in his being given the death penalty, Plato's Apology of Socrates; and the Platonic dialogues Crito and Phaedo, which give accounts of the life of Socrates between his trial and execution.