George Molnar came to see that the solution to a number of the prob-lems of contemporary philosophy lay in the development of an alter-native to Hume’s metaphysics. This alternative would have real causal powers at its centre. Molnar set about developing a thorough account of powers that might persuade those who remained, perhaps unknow-ingly, in the grip of Humean assumptions. He succeeded in producing something both highly focused and at the same time wide-ranging. He showed both that the notion of a power was central and that it could serve to dispel a number of long-standing philosophical problems. Molnar’s account of powers is as realist as any that has so far appeared. He shows that dispositions are as real as any other proper-ties. S...