Leibniz emphasised the similarity between time and space. The differences are striking, however, since time, unlike space, seems to have a direction: events seem to ‘move’ in time from the past into the present and into the future. But what does it really mean to say that events ‘move in time’? It seems rather too metaphorical to talk in these terms: an event cannot move in time in the sense in which a person can move in space. Perhaps we should say that time itself ‘moves’ or ‘flows’. On reflection, however, this idea is also strange. If time flows, how fast does it flow? There is a silly answer: ‘at the rate of one second per second’! But maybe the silliness of this answer suggests the emptiness of the question. ‘Flowing’ is a process that takes time; but time cannot itself take time! Although it is difficult to understand and make clear, something like the idea that time flows or has a ‘direction’ is nevertheless deeply embedded in the way we think about time. For example, there is nothing about the different dimensions of space – up–down, left–right, back–front – that prevents me from changing things in any one of those dimensions. But time is different: I can only change things in the present and the future. The ‘flow’ of time seems bound up with the idea of ordering events in a certain way (called ‘A-series’ below). Let’s consider the two ways of thinking about time and events. The first way of thinking is when we think of events as being in the past, in the present, or in the future. The First World War is in the past; it was in the present, and before that it was in the future. This way of ordering time was labelled the ‘A series’ by the British philosopher J. M. E. McTaggart (1866–1925). It is sometimes called the ‘dynamic’ time series because of its relation to the metaphor of the ‘flow’ of time. The A series is only one way we have of thinking about time. The other way is in terms of the idea of something being earlier than, later than or simultaneous with something else. This is what McTaggart calls the ‘B series’. (Dull names, I know. But they’ve stuck!) The difference between the A series and the B series is pretty easy to grasp. The A series represents time from a perspective or a point of view. To say that something is now or in the present expresses the point of view from which you are saying it. I cannot truly say that the assassination of Benazir Bhutto is now or in the present. But sometime in December 2007 someone could have truly said that. The B series, on the other hand, does not represent time from any particular perspective. To say that something is earlier, later or simultaneous with something else does not express the point of view from which you say it. I can say the assassination Bhutto was earlier than the resignation of Musharraf, and later than the military coup led my Musharrf, and in saying this I don’t presuppose that I am in any particular position in time. I can say this at any time and it remains true. Philosophers have debated the relationship between the A and B series. Is one more real than the other? Or do both express some kind of temporal reality? One of the most significant and influential answers to this question was given by McTaggart. McTaggart famously argued that time is unreal. This seems absurd. What can he mean by this? Here is the structure of the McTaggart reading I will assign to you. First, on p. 454, he distinguishes between the A and B series. Then he gives the first part of his argument 1–3: 1.The A series is essential to change: there can be no change without the A series (pp. 456–7). 2.Change is essential to time: there can be no time without change (p. 456). 3.Therefore the A series is essential to time: there can be no time without the A series (p. 455). The second part of the argument, 4–7, starts on p.462:
4.The A series is contradictory (p. 462)
5.Nothing that is real can be contradictory.
6.Therefore the A...