Abstract

This chapter proceeds as follows: in section II I discuss some crucial topics that can be regarded as a sort of starting point in Stoic epistemology: perception, concept formation, impression (phantasia) and assent. Some aspects of Stoic psychology are briefly discussed: unlike Plato and Aristotle, the Stoics argue for a materialistic soul. In their view, such a materialistic approach, while avoiding the ‘complicated way’ in which Plato and Aristotle explain the relation between soul and body (two entities supposedly distinct in nature), would contribute to a clearer account of our psychological functions and would explain more accurately the state of mind we call ‘knowledge’. Indeed perception, impression and assent are all psychological items; that is why, in the Stoic view, it is more reasonable to account for the way in which, for example, an extra mental object (what they technically call ‘impressor’) is able to produce an impression in one’s mind: both the impressor and the impression are bodies. Thus the unbridgeable gap between body and soul can be overcome. The Stoics hold that if the soul is in the body (as it is), and if the soul is able to move the body, the soul should be a body as well. Later (section III), after dealing with these matters, I discuss briefly the three states of mind which are closely linked to each other and which play a crucial role in Stoic epistemology: knowledge, opinion, and cognition. In this section both the Stoic criterion of truth and the Stoic theory of impressions are dealt with. The way the Stoics discuss impressions is particularly relevant, since they distinguished several kinds of impressions and one of them was declared to be ‘the criterion of truth’ (the ‘cognitive impression’; phantasia katalēptikē). Among Hellenistic philosophers the expression ‘criterion of truth’ became a trademark phrase when discussing the issue of knowledge. Finally, (IV) I summarize the achievements of this chapter and provide some concluding remarks.