Time Travel

Open Future

entirelyuseless Logic, Metaphysics, Science, Uncategorized , , , , , , , , ,

Let’s return for a moment to the question at the end of this post. I asked, “What happens if the future is indeterminate? Would not the eternalist position necessarily differ from the presentist one, in that case?”

Why necessarily different? The argument in that post was that eternalism and presentism are different descriptions of the same thing, and that we see the sameness by noting the sameness of relations between the elements of the description. But if the future is open, as Aristotle supposed, it is hard to see how we can maintain this. Aristotle says that the present is open to either having the sea battle tomorrow or not having it. With an eternalist view, the sea battle is “already there” or it is not. So in Aristotle’s view, the present has an open relationship to both possibilities. But the eternalist view seems to be truly open only to the possibility that will actually happen. We no longer have the same set of relationships.

Notice the problem. When I attempted to equate eternalism and presentism, I implicitly assumed that determinism is true. There were only three states of the universe, beginning, middle, and end. If determinism is false, things are different. There might be beginning, middle, and two potential ends. Perhaps there is a sea battle in one of the potential ends, and no sea battle in the other.

This suggests a solution to our conundrum, however. Even the presentist description in that post was inconsistent with an open future. If there is only one possible end, the future is not open, even if we insist that the unique possible end “currently doesn’t exist.” The problem then was not eternalism as such, but the fact that we started out with a determinist description of the universe. This strongly suggests that if my argument about eternalism and presentism was correct, we should be able to formulate eternalist and presentist descriptions of an open future which will be equivalent. But both will need to be different from the fixed “beginning-middle-end” described in that post.

We can simply take Aristotle’s account as the account of presentism with an open future. How can we give an eternalist account of the same thing? The basic requirement will be that the relationship between the present and the future needs to be the same in both accounts. Now in Aristotle’s account, the present has the same relationship to two different possibilities: both of them are equally possible. So to get a corresponding eternalist account, we need the present to be equally related to two futures that correspond to the two possiblities in the presentist account. I do not say “two possible futures,” but “two futures,” precisely because the account is eternalist.

The careful reader will already understand the account from the above, but let us be more explicit. The eternalist account that corresponds to the presentist account with an open future has multiple timelines, all of which “exist”, in the eternalist sense. The reader will no doubt be familiar with the idea of multiple timelines, at least from time travel fiction. In a similar way, the eternalist reworking of Aristotle’s position is that there is a timeline where the sea battle takes place, and another timeline where the sea battle does not take place. In this view, both of them “actually” happen. But even in this view, an observer in the middle location will have to say, “I do not, and cannot, know whether the sea battle will take place or not,” just as in Aristotle’s view. For the observer cannot traverse both timelines at once. From his point of view, he will take only one, but since his relationship to the two possibilities (or actualities) is the same, it is indeterminate which one it will be.

Even if one cannot prove my account of equivalence to be wrong, the reader may worry. Time travel fiction frequently seems incoherent, and this suggests that any view with multiple timelines may also be incoherent. But this potential incoherence supports the equivalence, rather than subtracting from it. For as we noted in the post on Aristotle, there is a definite appearance of incoherence in his position. It is not even clear how his view is logically possible. So it would not be surprising, but quite natural, if views which are intended to be equivalent to his position are also not clearly coherent. Nonetheless, the multiple timelines description does have some logical advantage over Aristotle’s position, in the sense that “the sea battle will take place in timeline A” does not even appear to contradict “the sea battle will not take place in timeline B.”

Turning Back the Clock

entirelyuseless History, Politics, Uncategorized , , , ,

Let’s look again at the center of Chesterton’s argument about turning back the clock:

There is one metaphor of which the moderns are very fond; they are always saying, “You can’t put the clock back.” The simple and obvious answer is “You can.” A clock, being a piece of human construction, can be restored by the human finger to any figure or hour. In the same way society, being a piece of human construction, can be reconstructed upon any plan that has ever existed.

Of course, one can physically turn a clock back. But as Chesterton notes, the idea that “you can’t put the clock back,” is a metaphor, not a literal statement. The metaphor is based off the idea that you can’t time travel to the past, and this is literally true, fortunately or unfortunately. The one who uses the metaphor intends to assert something stronger, however, and it is this stronger thing that Chesterton wishes to refute when he says, “Society, being a piece of human construction, can be reconstructed upon any plan that has ever existed.”

Yes, the human finger can turn back the clock. But what corresponds to “the human finger” in the case of society? Who or what has the power to reconstruct society upon any plan that has ever existed?

As soon as we ask the question, the answer is clear. Society has never been constructed upon any plan whatsoever; so neither can it be reconstructed upon any plan whatsoever. As Robin Hanson puts it, “no one rules the world,” so there is no way to construct society according to a plan in the first place. In particular, Hanson remarks regarding technology:

This seems especially true regarding the consequences of new tech. So far in history tech has mostly appeared whenever someone somewhere has wanted it enough, regardless of what the rest of the world thought. Mostly, no one has been driving the tech train. Sometimes we like the result, and sometimes we don’t. But no one rules the world, so these results mostly just happen either way.

Chesterton is free, as he says, to propose anything he likes, including bringing back the stage coaches. But we are also free to propose that the world would be better off if horses walked on their hind legs. The plans will meet with approximately equal success: getting the world to abandon automobiles and adopt stage coaches will not be much easier than getting horses to follow our suggestions.

Indeed, it is not impossible to bring back the stage coaches in the way that “bringing back last Friday” is impossible. But neither is it impossible for horses to walk on their hind legs in this way. Nonetheless both are impossible in the sense that physically turning back a clock is possible. Namely, no human being can either bring back the stage coaches or convince horses to walk on their hind legs, even though one can turn back a clock. One might have occasional success with either plan, but not overall success.

 

Convincing By Stories

entirelyuseless Ethics, History, Logic, Uncategorized , , , , , ,

When someone writes a story, something is being invented. It is not merely a narration of facts, since otherwise it would not be a story at all, but a history, or some other kind of account regarding the world as it is.

Nonetheless, there is always something in common with the real world, or something implicitly supposed to be in common with the real world. Thus for example The Betrothed presupposes and sometimes mentions actual facts about seventeenth century Italy, even while including an invented narrative about individual persons. Similarly, the film Interstellar  presupposes and sometimes mentions various scientific facts about the universe, even while adding various other things which almost certainly cannot exist in the real world, like time travel.

It is not difficult to see that it is essential to stories to have such a background in common with the real world, for if there were absolutely nothing in common with the real world, the story would be unintelligible. Among other things, a story must follow the laws of logic, at least most of the time, or it will be impossible to understand it as presenting an intelligible narrative. Consequently, a story will make sense to us insofar the background, real or supposedly real, makes the invented narrative a plausible and interesting one. Thus Manzoni’s novel must present a narrative that seems like a possible one in the context of seventeenth century Italy. Likewise, if the background implies that the invented narrative is highly implausible, the story will not make much sense to us. Thus, for example, while I enjoyed most of Interstellar, my experience was somewhat spoiled by the addition of time travel, and this generally tends to be the case for me when stories involve this particular idea. This is largely because time travel is probably logically impossible. To the degree that other people do not think that it is, or do not feel as if it were, it is less likely to disrupt their enjoyment of time travel stories.

The result of all this is that stories are one of the most effective ways to convince people of things. When we are giving our attention to a story, we are not in the mood for logical analysis or careful thought about the precise nature of the real world. And yet, in order to understand the story, we need to implicitly distinguish between the “real background” and the “invented narrative.” But in fact we may not be able to draw the line precisely; if someone does not know the details of the history of seventeenth century Italy, he will not actually know the difference between the things that Manzoni takes from the real world, and the things that Manzoni invents.The result is that a person can read the book, and walk away believing historical claims about Italy in the real world. These claims may be true, but they might also be false. And this can happen without the person having any explicit idea of learning history from a novel, and without noticing that he has become convinced of something which he previously did not believe.