According to Diogenes Laertius, the concept of ‘appearance’ played a central role in Stoic philosophy. As staunch corporealists, the Stoics believed that appearances are physical structures in our corporeal soul which provide the foundation for all our thoughts. One of the crucial features of appearance is that it is a representational mental state that has the ability to provide us with accurate awareness of the world through causal interaction between our senses and external objects, and thus supply the means for (...) acquiring knowledge about the reality. However, the Stoics recognized that we can also be aware and think of objects that are real but are not presently affecting our senses, as well as objects that are altogether fictional and thus incapable of ever interacting with our senses. Because of this, it was important for them to distinguish between representational mental states which are and those which are not caused by external objects at the moment in which they are formed. Chrysippus was one of the Stoics who paid special attention to this distinction; in a key text, Aet. 4.12, he is reported as reserving the name ‘appearance’ only for the former states, while for the latter he used a different term, ‘imagination’. (shrink)

The Stoics thought that knowledge depends on a special kind of appearances which they called ‘apprehensive’, which are by definition true. Interestingly, Sextus Empiricus reports in M 7.247 that they held that there are appearances that are true but that are not apprehensive because they are true merely by chance and thus cannot constitute knowledge. I believe that this suggests that the Stoics were aware of what is in modern literature known as the problem of epistemic luck. Unfortunately, Sextus’ report (...) leaves out a lot of important details, which makes it difficult to understand exactly which appearances the Stoics thought are true by chance, and why. I argue that the true non-apprehensive appearances in question here are imaginations, representational states which are not immediately caused by external objects through perception, but produced solely by the mind. I propose an explanation why the Stoics, who defined chance in terms of hidden causes, would have thought that imaginations can only be true by chance. The explanation stems from their view that the essential characteristic of imagination is that it leaves the actual cause of its representational content hidden from the subject. (shrink)

Cicero’s De divinatione portrays the Stoics as unanimous in advocating both natural and technical divination. I argue that, contrary to this, the earlier leaders of the school like Chrysippus had reasons to consider natural divination to be significantly epistemically inferior to its technical counterpart. The much more favorable treatment of natural divination in De divinatione is likely the result of changes introduced later, probably by Posidonius.