Chrysippus (c. 279–206 BCE)

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CHRYSIPPUS
(c. 279–206 BCE)

Chrysippus, the Stoic philosopher born at Soli, in Cilicia, became the third leader of the Stoa at Athens upon the death of Cleanthes, in 232 BCE. This post he held until his own death. Because of his defense of the Stoa against the attacks of Arcesilaus and the skeptical Academy, and undoubtedly also on the basis of his voluminous writings, it was said in antiquity "if there had been no Chrysippus, there would be no Stoa." He wrote 705 books, about half of which, judging from the catalog preserved by Diogenes Laertius, dealt with logic and language. None of his works is extant, though quotations from his books and assessments of some of his views have survived in the works of other ancient authors.

Chrysippus's epistemology is empirical. Presentations of objects are produced in the ruling part of the soul by movements engendered in the sense organs of the percipient. Illusory presentations can be distinguished from those that are veridical by deliberation, which consists in checking any given presentation against a fund of common notions, that is, families of remembered similar presentations; if the presentation is found to be sufficiently like some common notion, one may assent to it, thus acknowledging its veridical character.

Propositions are either simple or nonsimple. The truth condition of a simple proposition is the occurrence of the fact it conveys. The truth conditions of nonsimple propositions are functions of the truth-values of their ingredient propositions.

Chrysippus formulated five undemonstrated argument forms whose variables are to be specified by propositions. Among them are forms of the modus ponens and the modus tollens arguments. Arguments of varying complexity can be constructed by combining two or more of these basic forms. Chrysippus enjoyed a particular renown for his competence as a dialectician.

The moral philosophy of Chrysippus is concerned primarily with a statement of the final end of life and the relation of other things to it and with a consideration of the emotions and therapy for those enslaved by them. The final good is "to live in accordance with one's experience of the things which come about by nature." This is equivalent to living in accordance with reason, which in man supervenes upon instinct as a guide in life. The excellence of reason is wisdom, or knowledge of what is really good and what is really bad. Chrysippus's view in regard to the source of this knowledge is ambivalent. On the one hand—and this is obviously the doctrine that coheres best with his epistemology—it derives from generalizations made upon particular experiences. On the other hand, there are fragments implying that his knowledge is innate.

Emotions are great obstacles to happiness and are to be totally eradicated. In keeping with his monistic psychology, which rejects the Platonic doctrine of a tripartite soul, Chrysippus conceived of an emotion as a recently formed false judgment about the goodness or badness of something; such a judgment causes "a forceful and excessive impulse." Therapy for the emotions consists in persuading their victims that the judgments constituting the emotions are false.

The dominant motifs of the natural philosophy of Chrysippus are monism and determinism. The one substance that converts periodically into an elaborately structured universe has two constant aspects, a passive one and an active one. The passive is matter; the active is identified variously as reason, pneuma (spirit or breath), and God. Chrysippus regards so-called individual substances not as discrete units of matter but rather as "parts" of one primary substance. Everything that oc-curs is controlled unexceptionably by fate, which is "the continuous causal chain of the things that exist." Nothing comes about except in accordance with antecedent causes. Even in the case of states of affairs that might seem to be of a spontaneous or uncaused nature, "obscure causes are working under the surface." Chrysippus believed that humans were responsible for their conduct, and he sought in several ways to show that such a belief was not undermined by the rigorously deterministic view he espoused.