This chapter explains something useful regarding issues coming under the heading of ‘mental causation’. The mental causation debate is customarily conducted in terms of mental states, of which beliefs are supposed to be leading examples. This choice of term is an early sign of confusion. Despite the ‘state’ talk, the discussants in mental causation debates really do understand that the candidates for causes are events – they just call them ‘occurrents’. Part of the background of the mental causation debate is the assumption that mental states are physically realized. According to neuroscience, the prominent candidates for realizers of dispositional mental states are synaptic strengths. One of the most interesting developments in the discussion of mental causation is S. Shoemaker’s work on physical realization, and his subset view.