Publisher Summary This chapter discusses some general methodological questions about the nature of psychology as a science by assuming one know very much more than one do about the brain and the nervous system of man. Psychology is treated as a subject that deals with phenomena described by concepts that involve intention, belief, and conative attitudes like desire. Among these actions, decision, memory, perception, learning, wanting, attending, noticing, and many others is included. Attempts have been made, to show that psychology can do without some or all of these concepts, for example by trying to define concepts like belief or desire in terms of concepts more behavioral, or otherwise more like the concepts used in the physical sciences. The distinction between individual events and sorts, and the supervenience of the psychological on the physical, are related.