Consider three fundamental beliefs we have about the world (so fundamental
that we would rarely, if ever, articulate them): that change is going on
constantly, that changes are caused, and that there are constraints on what
changes are possible. If we then ask: but are these beliefs true? and: how is it
possible for them to be true, if they are? we have summarized many of the
central concerns of metaphysics, the philosophical study of what there is. These
are the questions with which the first philosophers were concerned. Such
questions are paradigmatic of philosophical enquiry, and one cannot progress
very far in answering them without considering problems about time. One of
the purposes of this Introduction is to make those connections clear.
The three fundamental beliefs mentioned above introduced three central
concerns: change, causation, and possibility. These concerns are unifying
themes in the essays of this volume.