Abstract

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’.