At least movement is relatively clear, and in principle perceivable. But what is a "hypothetical or actual possibility of change"? (Are you distinguishing two different kinds of possibility here, one hypothetical, the other actual, or does this phrase somehow refer to one thing?) ... You'd need a rather thorough account of what "possibilities" are, in particular non-actual possibilities, to make this answer be an improvement on the earlier one .... (You might read Augustine's famous treatment of time, where he explores the relationship between time and motion: in his Confessions, ch. 11 .....)

hope that's a start!

ap

good question!

perhaps distingish between our being justified in using the device for its purpose from its actually succeeding in fulfilling its purpose. in your coin case you would not be justified in believing the answer the coin gives -- but the answer might (luckily) actually be correct. similarly for the clock case -- its being broken means you are not justified in using it to learn the time, but sometimes unjustifiable processes do yield the correct result (even though you're not justified in believing it) -- so on this view the clock IS right twice a day ....

hope that helps

ap

Is the idea of backwards causation coherent? It seems not, as you could, for example, cause earlier events, such as your own birth, not to have happened. There is also the famous "bilking" (cheating) argument due to Max Black, according to which you can prevent the future cause of something that has already happened from occurring. All the same, philosophers, particularly Michael Dummett, have taken the idea perfectly seriously, and defended it. You write that you doubt that a scientist would take the idea seriously, but plenty of physicists, including Richard Feynman, have indeed used the idea for a variety of purposes, including the remarkable idea of positrons running backwards in time.

I have nothing to add here except to say that this question has often occurred to me -- has anyone truly believed (say) that when spring rolls around each year, it is precisely the very same "time" that it was the year before, rather than being merely a "similar" environment recurring? I suppose if something like Nietzsche's 'eternal recurrence' were the case (taken literally), then there could be some question of a genuinely recurring ie cyclical time -- but even then wouldn't it be far more plausible to hold that time remains linear even if the events occurring in time might go through cycles?

Will be curious if anyone else weighs in with an endorsement of the opposing view -- or even of the claim that any culture has endorsed such a view.

best, ap

This is an excellent question and one that is much debated historically and today. It has implications about freedom and determinism, logic, and the philosophy of God, good and evil. It seems that classical logic requires that propositions are either true or false. "Barack Obama is the forty-fourth president of the USA" appears to be a proposition. And we have found it to be true. But in that case, it seems that Obama could not have failed to have won the election against McCain. It has seemed to some (but certainly not all) philosophers that this would mean Obama's election was fixed in some sense, perhaps determined. Some who worry about this problem are theists who think that if God knows from eternity that in August of 2011 you would ask your question, then there is no possibility that you would not have typed in and submitted your question to Askphilosophers. For many theists, it is vital to affirm that creatures / human beings have free agency, otherwise it would seem that God has determined humans to be evil. The other worry about what is called future free contingents (the fancy term for propositions that refer to future events that appear to involve freedom and contingency) has to do with whether there even could be such future propositions. It seems that for a proposition to be true there must be SOMETHING in virtue of which the proposition is true. But in the 19th century, Obama did not exist; he did not exist then, nor was he existing in the 21st century. From this line of reasoning (which was probably Aristotle's), we should hold that propositions involving future free contingents are neither true nor false. Theists who take this position (like Richard Swinburne) contend that even an omniscient God does not know about future free continents. According to Swinburne, God knows all possible truths and because propositions about future free contingents is neither true nor false and thus cannot (by definition) be known by any being of any kind, such propositions about the future are not the sort of thing that even God knows.

Thank you for your question. Let me touch it up just a bit:

There are no gravitational fields in general relativity over and above the curvature of space(time). In the spirit of the question, I will assume that the spacetime geometry is unchanging.

An observer might be able to notice the passing of time in lots of ways (e.g., from his own heartbeats or passing thoughts or wristwatch). I presume that the question is asking whether the observer could notice it on the basis of some observed changes in the region of space in question.

I am inclined to think not. Nothing is changing there. If spacetime geometry were changing, then the passage of light through the region to us would betray the change to us. But the question stipulates that nothing passes through the region.

I'm not quite ready to go along with my colleague's answer, but my answer isn't any more hopeful.

If time has the structure of the real line (as we usually think) then even if it's infinite, every moment is only a finite time away from now. (Compare: every real number is only a finite distance from 0.)

But even if time is infinite in the way the real number line is, it doesn't follow that there will be a duplicate of you somewhere off in the future. To get that conclusion woud take a lot of extra and optional premises. More important, even if there will be a duplicate of you someday, there's no good reason to think it would be you, nor is there any good reason to think that you could look forward to its experiences. (These two aren't quite the same issue, as it turns out.)

Clearly there's a lot in the background here. If you're interested in more reading on the core problem, i.e., the problem personal identity, you might have a look at Martin and Barresi's anthology, called Personal Identity.

I don't see why since if time is indeed infinite the point at which that occurs may be infinitely in the future. Not a great deal to anticipate in that case, then!

Here are some questions about time that are not scientific but are philosophical. Does time flow? Does it pass? What does it pass? Does it move? If so, how fast? If speed (s) = d/t, what is d/t when s is the speed of time? What temporal distance does time travel in a unit time? Surely the unity distance. But then the speed of time is 1 sec. per sec. How can time be measured, as the past does not exist and the future does not exist and the present is merely a point - nothing to measure there! - dividing the past and future? Does time exist? What (if anything) is it made of? Is time travel possible? In a completely unchanging universe, would time pass anyway? If every true statement corresponds to a fact, how can statements about the future be true now, in the present, as there are no facts about the future now, in the present? If there were, they wouldn't be future. Does it mean anything to say that time has a direction? What does it mean? If omelets came first and then eggs afterwards, time would surely still be going forwards, whatever that means; it's just that omelets would come first and eggs afterwards. And (as Andrew points out) how - in what way - do we experience time? This last question, though, might be thought to have a wholly psychological sense. Perhaps there is no such thing as the experience of time itself, but only of things changing. Would there be any difference in our experience of the world if we did not experience time as such? In fact the conceptual problems of time are interesting partly because so little in the way of answers can be extracted from science. In "Time and Physical Geometry" (1967) Hilary Putnam took the view that science gives the answer to problems about time. Science tells us that the death of Mr. A. is earlier in your reference frame than the death of Mr. A in my reference frame. That leaves a huge philosophical problem about the place of Mr. A's death in reality. One can see how simultaneity is relative to a reference frame, but it is much harder, if not impossible, for philosophical reasons, to see how the reality of something like Mr. A's death could be taken relative to a reference frame. But this is implied by its position in the temporal order.

Good question. But why can't it be both scientific and philosophical? Much of the philosophy of time -- dating back long before serious scientific investigation on time (which I'll arbitrarily date to 17th century or so) -- involves reflection on our conscious experience of temporality -- and most of that reflection still is valuable and insightful even as science has progressed to very different understandings of the nature of time ... So there's still plenty of room to philosophize about time, about our experience of time, even INDEPENDENT of whatever's going on in science ....

best,

ap