The Greek philosopher Chrysippus (ca. 280-ca. 206B.C.) was the first systematizer of Stoic doctrine and should probably be credited with much of that Stoic logic and language theory which has impressed a number of 20th-century philosophers.
Chrysippus was born in Soli in Cilicia. As a young man, he made his way to Athens, where Cleanthes was head of the Stoic school. For a while Chrysippus seems to have been drawn to the teachings of Arcesilaus, head of the Platonic Academy and initiator of the skeptical phase in the history of Platonism, but eventually threw in his lot with Stoicism.
Any influence exercised by Cleanthes, however, must have been at a doctrinal level only; their personal relations do not appear to have been of the happiest. Chrysippus clearly had more respect for Cleanthes' beliefs than for his ability to defend them; on one occasion he asked Cleanthes to supply him with the doctrines, and he himself would supply the proofs. According to his ancient biographer, he eventually broke with Cleanthes and set up as a Stoic teacher in his own right. In 232 B.C. he succeeded Cleanthes as head of the Stoa and retained the chair till his death.
Chrysippus's numerous writings—he wrote 705 pieces, all of which are lost—mark a move away from the "poetic" stoicism of Cleanthes to a more rigid and logical systematization of the doctrine. There was a saying in antiquity that "but for Chrysippus there would have been no Stoa." A cardinal point of his system, indeed the one which underpinned the whole structure, was his conviction that absolute certitude is attainable by man. In this he was attacking the fundamental tenet of the Skeptical Academy, which laid stress on the Socratic method and the epistemological open-endedness of so many of Plato's dialogues. The continuing influence of the same skepticism on Chrysippus, however, can be seen in his willingness to examine counterarguments; in this respect he seems to have worried fellow Stoics, who felt that he often stated the anti-Stoic case more forcibly than his own.
While in general Chrysippus systematized doctrines propounded less systematically by his predecessors Zeno and Cleanthes, he seems to have made contributions of his own in the matter of basic epistemology; in his assertion that feelings are in fact judgments of the mind; in his conviction that the mind is purely rational, rather than a composite of rationality and irrationality; and, perhaps, in his anthropocentric view of the plant and animal kingdom.
For the fragmentary remains of Chrysippus's doctrines the most convenient source is the third volume of C. J. de Vogel, ed., Greek Philosophy (3 vols., 1950-1959; 3d ed. 1963). For discussion of particular doctrines see Josiah B. Gould, The Philosophy of Chrysippus (1970).