[...]... pastness of members of the series of clock times But more substantially, in the opinion of most advocates of the tensed view, it has the effect of constantly eating away at the realm of the merely potential, by forcing future potentialities either to be actualized or to be relegated to the status of mere might-have-beens That is not to say, of course, that the advance of the present determines which they... that the moving present advanced along the series of clock times It becomes clear, then, why we are unable to provide, in the same terms that we express the rate of other changes, an informative answer to the question at what rate the moving present is advancing along the series of clock times The reason is that, whenever we ascribe a rate of change to anything at all, other than the passage of time, ... way of reinforcing this line of argument First, it is characteristic of any genuine change that it has effects: it carries further changes along with it Can we say this, then, of the passage of time, assuming it to be a reality? Well, yes It is true, 18 The Labyrinth of Time of course, simply by definition, that the advance of the present, if there is such a thing, constantly alters the degree of futurity... trivially a function of clock time; and clock time is only trivially a function of itself In general, then, change over time, as proponents of the tenseless view understand it, must involve both a range of attributes and the series of clock times At the root of Smart’s first objection is the fact that, when we try to construe the passage of time in the way that advocates of the tenseless view would have... opposing conceptions of time are frequently called, instead, the A theory and the B theory, with their respective advocates being referred to, correspondingly, as A-theorists and B-theorists This is because proponents of the tensed conception of time are committed to the view that any adequate account of time must make reference to now-relative times, which constitute the A series, whereas their rivals regard... (see Fig 1.2) This station corresponds to the base of the trunk in our tree model and to the instant of the Big Bang, perhaps, in reality 12 The Labyrinth of Time Fig 1.1 Branch points in the passage of time Two Concepts of Time 13 Big Bang Station Fig 1.2 Time s railway Trouble on the Line With this analogy in mind, let us now consider the following passage from the influential philosopher J J C Smart... amounts to the advance of the present, 2 The Labyrinth of Time which we all share For that reason alone—quite apart from the notorious ‘paradoxes’ to which it gives rise—few people would take seriously the idea of time travel as envisaged in science fiction Given that it would contradict the presumed universality of the passage of time, it is difficult to believe that, while the rest of the world marches... perspective of the tensed view, is that the passage of time cannot meaningfully be construed as merely one process of change amongst others (To that extent our train analogy is indeed defective.) An advocate of the tensed view should not, that is to say, regard the passage of time as a process of change that exists in addition to such processes as the change of colour of the autumn leaves or the change... speed is the flow of time? Seconds per what? Moreover, if passage is of the essence of time, it is presumably the essence of hypertime, too, which would lead us to postulate a hyper-hypertime and so on ad infinitum (Smart 1967: 126) 14 The Labyrinth of Time These observations appear, at first sight, to be very persuasive But on closer inspection of his argument, we find that Smart is really begging the. .. the clock times as moving Regarded in this way, clock times are to be viewed as advancing towards the present, passing it and then receding into the past Philosophically speaking, there is nothing to choose between these two ways of thinking of the passage of time, just as, 6 The Labyrinth of Time according to modern physics, there is nothing to choose between regarding a train as moving and the track .