Introduction

McTaggart famously argued that time is unreal. Today, almost no one agrees with his conclusion. But his argument remains the locus classicus for both the A-theory and the B-theory of time. I want to show how McTaggart's argument provided the impetus for both of these opposing views of the nature of time. I will also present and defend what I take to be the correct view of the nature of time.

McTaggart begins by noting that, when we think about when, in the temporal order of things, an event is located, there are two ways in which we can do this. On the one hand, we can locate an event as in either the past, the present, or the future. Once we have designated an event as occurring, say, three days ago, then every other event temporally related to that event will have some determinate location in either the past, the present, or the future. McTaggart called the series of events ordered in this way the A-series. But we can also locate events in time without reference to the past, present or future. We can locate events as temporally related to each other. We say that an event is earlier than, later than, or simultaneous with some other event. We can use these relations to order every event in a temporal series. McTaggart called the series of events generated in this way the B-series.