Steven Savitt

There is a wide-spread belief that we know more about the past than we do about the future. It may be difficult to express the content of this belief exactly and it may turn out that, when we find some precise expression of this belief, it is not so obviously true. I shall assume, however, that there is something to a belief shared not only by eminent philosophers but by cultures wholly distinct from our own, as the following quote indicates.We know where the future is. It’s in front of us. Right? It lies before us—a great future lies before us—we stride forward confidently into it, every commencement, every election year. And we know where the past is. Behind us, right? So that we have to turn around to see it, and that interrupts our progress ever forward into the future, so we don’t really much like to do it.

J. M. E. McTaggart, in a famous argument, denied the reality of time because he thought that passage or temporal becoming was essential for the existence of time and that passage was a self-contradictory concept. This denial of passage has provoked a vast literature, two of the most important contributions being C. D. Broad’s painstaking defence of passage in his Examination of McTaggart’s Philosophy and D. C. Williams’ dazzling condemnation of it “The Myth of Passage.” A careful reading of these apparently opposed essays reveals that there is a common notion of passage that both philosophers endorse, the successive occurrence of sets of simultaneous events (assuming classical or Newtonian spacetime structure as background). This unexpected agreement provides a notion of the passage of time that, I claim, is lean enough to survive the criticisms of passage-deniers yet robust enough to satisfy the requirements of passage-affirmers. I undertake to describe and defend this notion.

ABSTRACT Kit Fine recently described and defended a novel position in the philosophy of time, fragmentalism. It is not often that a new option appears in this old field, and for that reason alone these two essays merit serious attention. I will try to present briefly but fairly some of the considerations that Fine thinks favour fragmentalism. I will also weigh the merits of fragmentalism against the view that Fine presents as its chief rival, relativism, as well as the merits of both against the view that he calls anti-realism. Along the way, we should pick up a clearer picture of fragmentalism itself.

ABSTRACT In his contribution to this issue, “A and B Theories of Closed Time”, Phil Dowe argues that A- and B-theories of time are equally compatible with closed time, though it is commonly supposed that only B-theories are compatible with it. With some reservations to be noted below I agree with Dowe’s general conclusion, but in the course of his argument there are a number of false statements and misrepresentations of detail that require comment. I will not be able to deal with all of them in this brief note.

While experience tells us that time flows from the past to the present and into the future, a number of philosophical and physical objections exist to this commonsense view of dynamic time. In an attempt to make sense of this conundrum, philosophers and physicists are forced to confront fascinating questions, such as: Can effects precede causes? Can one travel in time? Can the expansion of the Universe or the process of measurement in quantum mechanics define a direction in time? In this book, researchers from both physics and philosophy attempt to answer these issues in an interesting, yet rigorous way. This fascinating book will be of interest to physicists and philosophers of science and educated general readers interested in the direction of time.

One of the questions that is addressed, from various perspectives, is the origin of time-asymmetry. Given the time-symmetry of the dynamical laws, all inferences about the future that are derivable from a dynamical theory are matched by inferences about the past. For Huw Price, who discusses the origins of cosmological time asymmetry, this is reason to treat all time-asymmetric cosmological theories with caution. He dismisses both the inflationary model and Stephen Hawking’s proposal to account for time-asymmetry with his famous “no boundary condition.” Instead, on the basis of the fact that we have no a priori reasons to distinguish between initial and final conditions, he advocates Gold’s time-symmetric model for the universe, in which the thermodynamical arrow of time is tied to the expansion of the universe, so that in the contracting phase towards the big crunch, entropy decreases.

Barry Dainton wrote Time and Space “to provide an introduction to the contemporary philosophical debate that presupposes little or nothing by way of prior exposure to the subject, but that will also take the interested and determined reader quite a long way”. He has achieved much of what he intended in this difficult enterprise. He covers the major arguments in a fair-minded way, writes clearly, and has found a good illustrator to provide a host of diagrams that his student readers in particular will find helpful. The book also has a helpful glossary and list of web resources, as well as a brief bibliography and index.

The distinction between presentism and eternalism is usually sought in some formula like ‘Only presently existing things exist’ or ‘Past, present, and future events are equally real’. I argue that ambiguities in the copula prevent these slogans from distinguishing significant opposed positions. I suggest in addition that one can find a series of significant distinctions if one takes spacetime structure into account. These presentisms and eternalisms are not contradictory. They are complementary elements of a complete naturalistic philosophy of time.

John Earman's new book,World Enough and Space-Time, is a brisk account of the controversy between space-time absolutists and relationists. The book is intended, one is told, to be “appropriate for use in an upper-level undergraduate or beginning graduate course in the philosophy of science”, but Earman's no-holds-barred approach to the mathematics of space-time theories will have bludgeoned most philosophical readers, undergraduate or beyond, into submission long before it is revealed that Pirani and Williams “have studied the integrability conditions for Born-rigid motions in curved space-times and have shown that space-times of Petrov types II, III, and N do not admit of nonrotating Born-rigid motions”. I say this sadly, because Earman's book is a discerning review of an important literature, and most of its main arguments can be grasped even if some technical details remain out of reach. The more you reach for those details, the more compelling the book will become.