The Stoics on Determinism and Compatibilism (review)

Stoic determinism has been the object of important work recently, most notably Susanne Bobzien's monumental work, Determinism and Freedom in Stoic Philosophy. Ricardo Salles provides a fresh and distinct perspective. He challenges several points in Bobzien's work, so his book serves as a good complement to Bobzien's arguments.

The first part of the book is an analysis of the Stoic arguments for determinism. The rest of the book discusses four Stoic theories concerning determinism. Three of these theories defend a form of compatibilism. The fourth, presented by Epictetus, tries to resolve a problem arising from Chrysippus's compatibilism.

Chapter one focuses on Chrysippus's argument for fatalism from the principle of bivalence (PB). Chrysippus held that propositions about the future cannot be true now unless there is a cause now of the future event. Since (PB) entails that future propositions are either true or false now, causes now exist making every such proposition or its contradictory true now. Thus, everything that happens has a cause, since the existence of any causeless event would contradict (PB). Salles clearly contrasts Chrysippus's causal fatalism with the non-causal fatalism attacked in the De Interpretatione. While the latter simply infers the necessity of future events from (PB), Chrysippus's fatalism requires two further premises: first, prior truth implies causation; and second, that causes necessitate their effects.

In chapter two, Salles examines more closely this second premise. Salles locates support for causal necessity in the theory of eternal recurrence. Since every world is identical in all details, every cause has exactly the same effect every time it recurs. Salles concludes that the two basic theses of Stoic determinism (everything has a cause, and every cause must have the effects it does) follow from (PB) and eternal recurrence.

The remaining four chapters discuss the four Stoic theories. Chapter three treats the Stoic response to the objection that internal causes are necessary for freedom. Chrysippus responds by rejecting the premise that external causes fully determine their effects. Actions also involve internal factors, namely assent. Illustrating this is a cylinder, whose motion is initiated by a push but whose continued rolling is the result of the cylinder's shape. Likewise, an external impressor causes the agent's impression, but the agent's nature causes the assent.

Salles argues, in chapter four, that Chrysippus advanced a "Frankfurt-style" argument against the claim that responsibility requires the capacity to do otherwise. Even though events are necessitated, we are responsible for them if they occur through us in accordance with our nature. Humans possess the faculty of krisis, which allows us to consider our first impressions rather than automatically assent to them. My rational assent to an impression suffices to make the impulse and the corresponding action mine.

In chapter five, Salles argues that the Stoic compatibilist theory described in chapter four is Chrysippean, and compares that argument, (T3), with two other Chrysippean compatibilist arguments. One of those theories is the anti-externalist argument discussed in chapter three, (T1). The remaining theory, (T2), is the modal argument that actions may be both determined and contingent. Salles argues that (T3) is Chrysippean and formed part of a single strategy with (T1) against an Aristotelian form of incompatibilism. Salles addresses two questions here. Is (T3) early or late? And, if it is late, is it simply a development of Chrysippus' thinking, or a break from it? Salles challenges Bobzien's speculation that (T3) was developed by the later Stoic Philopator. The arguments differ because (T3) focuses on human reasoning and deliberation, while (T1) has a broader goal of showing how the internal character of an object—human or otherwise—is a factor in determining its behavior. Salles argues that the two theories are consistent and therefore need not be attributed to two authors. While (T1) answers the externalist objection, (T3) is meant to discharge the "dual capacity" objection. Salles concludes chapter five by discussing the connection between (T3) and (T2). He...