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Saturday, March 01, 2008

Jumpin' Jehoshaphat!

Paul Manata has been on a safari Down Under, busily hunting an endangered marsupial called the Kangaroodort. In this connection, I’d like to draw our attention to an intriguing parallel between objections to the coherence of prayer in Calvinism and the coherence of time travel and/or retrocausation. Time travel is often considered to be incoherent because it generates antinomies like the Grandfather paradox. However, Barry Dainton has drawn an important distinction between *changing* the past and *affecting* the past.

The past is widely believed to be unalterable. This is known as the accidental necessity of the past. And, in Calvinism, the future is foreordained, so there’s a certain symmetry between the past and future. That, in turn, is analogous to Dainton’s “static” view of time. So, although Dainton evokes his distinction to establish the coherence of time travel, this distinction, if valid, would also be applicable to the Reformed doctrine of prayer—which is ordinarily forward-looking. The analogy would be even tighter in the case of a Reformed philosopher like Paul Helm who espouses the B-theory of time.

Of course, Calvinists believe in predestination and prayer alike because both of these are revealed truths. So their mutual truth, as well as our faith in their mutual truth, is not dependent on philosophical arguments one way or the other. But since objections to Calvinism always come down to moral or philosophical objections, as—indeed—we see in objections to the Reformed doctrine of prayer, it’s worthwhile to have a look at Dainton’s discussion of time travel:

“Another common misconception, a more serious one, is embodied in arguments such as the following:

‘But couldn’t we *travel into the past* and witness for ourselves the Egyptians building pyramids?…there is a problem, however. Those centuries have passed; the events have happened; they’re over. And they all happened *without you*—you weren’t even born until the twentieth century. The ancient civilizations came and went, and you weren’t anywhere in that picture. How then can you say that you could now *go back* there and *be* among the people then living? It all happened without you, and now you want to say that you could go back and participate in it, that is, that it did *not* happen without you?’ (Hospers 1997:121),” B. Dainton, Time & Space (McGill-Queen’s 2001), 112.

“There are two key assumptions made here: the past cannot be changed; and backward time travel involves changing the past. Are these assumptions true? It depends on the nature of time…the idea that the past could be changed is highly counterintuitive Not only does it entail two conflicting but true accounts of what occurred at a given time, but it is quite likely that changes in the past produced by a time traveller’s arrival will have wider ramifications, and require the wholesale replacement of the subsequent timeline. Consider a scenario familiar from the Terminator films…one entire stretch of human history simply vanishes and another stretch is immediately created to take its place. Is this scenario absurd? I am inclined to think that it is,” ibid. 112-13.

“But don’t forget, we are currently assuming the block view [of time] to be true, and in this context it is simply a mistake to suppose that backward time travel *would* bring about changes in the past of the problematic sort just envisioned. If the universe consists of a single block of times and events, what occurs at a given time is fixed and unchangeable. This does not mean that you cannot go back to 3000BC and assist with the building of the pyramids; what it means is that if you do travel back and assist, *that* you do so is as true now as it was then. It is true at *all* times, including those that occur before you set off. You may have been born in1975, but unbeknownst to you and your parents this was not your first appearance in the world’s affairs: you first entered history as a thirty-year old, assisting with the building of the pyramids several thousand yeas previously. In short, everything that you ever do as a time traveler is *built into the past* before your first journey. Prior to your departure you do not remember being in Egypt all those years ago, but this is because the time you spend there lies in your (personal) future. Of course, if you left any traces of your visit—perhaps you carved your initials on a sarcophagus—these may well be discovered prior to your departure. It is one thing to *affect* the past—to contribute to what occurred at the times in question—quite another to *change* it. You can certainly affect the past—your initials are testament to that, and there are Egyptians slaves who are glad of your help—but you did not change it. The building of the pyramids only occurred once, and you were there at the time,” ibid. 113.

“So the argument fails. But the mistake on which it is founded is easily made. In imagining how things were in ancient Egypt we envisage ourselves *being present* there; since we naturally assume that times later than the present are unreal, it seems absurd to think someone from the twentieth century could put in an appearance; the future from which they would supposedly emerge is nonexistent. Consequently, if someone from the twentieth century *were* to travel back, it seems that they will be emerging into a history that originally unfolded in their absence. All this shows, however, is that backward time travel is problematic in the context of certain dynamic models of time. Since we are currently working within the confines of the static block view, this is an irrelevant result,” ibid. 113.

Now, simply invert the comparison from the accidental necessity of the past to the future, and you can see how an agent could *affect* the future (through prayer), even if the future were foreordained, without *changing* the future. Hence, there’s nothing incoherent in the idea that prayer makes a difference to what would otherwise have come to pass in the absence of prayer even though the future is unalterable.

And if you find this analysis difficult to follow, then don’t raise philosophical objections to Calvinism. Stick with exegesis, which should have been the yardstick all along.

2 comments:

  1. Steve, how dare you post something over the Arminian's heads. I mean, at least make it a fair fight.

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  2. Brian Greene also made the same argument in The Fabric of the Cosmos (if I recall--it could have been his other book though).

    From the standpoint of physics, time is just as "solid" regardless of the direction of time's arrow. Indeed, given Einstein's relativity theory, time is relative to distance, velocity, and a host of other factors such that there is no such thing as two "simultaneous" events. If they are simulatenous for one observer, they are not for another obsever (the classic train example illustrates this).

    The illustration of this is often as looking at time like a loaf of bread. You can cut the loaf different ways. We think of a slice going vertically from top to bottom, where a point at the top of the loaf is "simultaneous" with a point at the bottom of the loaf. But if you cut it at a thirty degree angle, the points on the top and bottom of the loaf no longer line up and "simultaneous" events occur at a different time than the vertical slicing. Since relativity demonstrates the validity of those various angles, "simultaneous" events can occur across a wide spectrum of time. Thus, there is a "cut" of time where the creation of the universe is simultaneous with the destruction of the universe.

    However, while the "slice" of time is different, the actual "loaf" of time remains constant. Therefore, if one were to go back in time, one would have always gone back in time. Because time itself is just as much an object, the events of time do not change.

    Thus, as Steve quoted Dainton, if from your perspective you go back in time to work on the pyramids then this has always been true. It was true then, it will be true in the future. It will be true even for the time slice that views the creation of the universe as simultaneous with its destruction (a viewpoint, I might add, that's probably equivalent to the photon's perspective).

    This is why I love physics :-) Because it's so freaking cool!!!!

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