What is metaphysics? An answer to this question requires a specification both of the scope of metaphysics—that is, of the nature of the questions that metaphysicians raise and attempt to answer—and of the methods that they employ in this enterprise.

The Scope of Metaphysics

As regards scope, a natural answer is that metaphysics is concerned with the investigation of the ultimate nature of reality, where this involves the attempt, first, to arrive at the most fundamental truths about what exists, and, second, to provide an account of the concepts that are involved in such fundamental truths. This characterization immediately gives rise to the question of the relation between metaphysics and science. The goal of physics, surely, is to arrive at the ultimate truth concerning the nature of the physical world. Similarly, the goal of psychology is to determine the ultimate...