Abstract
THE NATURE OF THINKING HAS PERSISTED in eluding attempts at definition. This, I will suggest, is because thinking is heterogeneous: there is no one thing that is called thinking. In this paper, I will describe five forms of thinking that are basic, in the sense that they are episodes of thinking that do not have as parts other episodes of thinking. My aim is not to suggest that every process or activity of thinking can be analyzed, without remainder, as a compound of these five basic forms of thinking, plus perhaps a few other ones. The reason for turning to episodes of thinking that are not composed of further episodes of thinking is to show that thinking is heterogeneous in a nontrivial sense. Although all five basic forms of thinking are episodes that are in some sense "about" or "directed toward" something, it will become clear that beyond this property of intentionality they do not share a single further property.