Abstract
This is an excellent book, which any philosopher who works on this topic can read with profit. The author has read, thought about, and in many cases laid under contribution, almost everything of significance that has been written about this important metaphysical topic. His conclusions seem to me sensible and plausible. He conscientiously mentions earlier articles that he has published on the topic, and indicates where he would now amend the views expressed there. As I shall indicate, the book seems to falter towards its very end, where the ultimate questions raised by his approach are taken up. There the standard of reflection and argumentation seems to fall away. But he has led us to the point where further thought and further arguments, either by himself or others, can most usefully be deployed.