Abstract

This chapter considers the status of the PSR for the Stoics, Epicureans, and Skeptics as falling along a spectrum of attitudes to the demand for explanation. The PSR is strongest with the Stoics, but also limited by their brute commitment to two eternal, ungenerated, and fundamental principles that are the source and explanation for everything there is. With the Epicureans, the PSR is strong yet limited in similar ways, by the fundamentality of the atoms and eternality of their motion, but also much more severely blunted by the famous doctrine of the swerve, according to which atoms veer off at uncertain times and places. Finally, with the skeptics there is a tantalizing tension between the pervasive use of the PSR to undermine all dogma and the application of the PSR to itself, so that there is no more reason to endorse this guiding skeptical principle itself than to reject it.