A Crucial Distinction in William of Ockham’s Philosophy of Mind: Cognitio in se/cognitio in alio

Abstract

William of Ockham frequently mentions a distinction between two modes of cognition: in se and in alio. The aim of this chapter is to show that this distinction raises some important problems for his philosophy of mind and more broadly for his nominalism. The main issue is the possibility of an externalist theory of mental contents. For, Ockham affirms that no material substance is cognized in se. But if only accidents are cognized in se does this mean that material substances are necessarily cognized in alio? How could this “something else” lead us to the cognition of something we have never experienced? The difficulty here is how we should understand his view concerning the acquisition of simple substance concepts like “man” or “horse.” On the one hand it seems that we have no direct acquaintance with substances. On the other hand, he says that these concepts, equivalent to simple natural kind terms in the mind, directly refer to singular substances thanks to external relations of causality and likeness, on which their signification is based. This chapter suggests that the evolution of Ockham’s theory of concepts during his career is probably the key for our understanding of this crucial distinction.