Tuesday, September 22, 2015

Change and presentism

This post is an illustration of how widely intuitions can differ. It is widely felt by presentists that presentism is needed for there to be "real change", that the B-theory is a "static" theory. But I have the intuition that presentism endangers real change. Real change requires real difference between the past states and present states, and real difference requires the reality of the differing states. But if there are no past states, there are no real differences between past and present states, and hence no change.

Of course, a presentist can say that although a past state is unreal, there can nonetheless be a real difference between it and a real present state, just as there can be a real difference between the world of Harry Potter and our world, even though the world of Harry Potter isn't real. In a sense of "real difference" that's true, I agree. But not in the relevant sense. Change is a relation between realities.

The presentist can also insist that my line of thought is simply a case of the grounding problem for presentism, and can be resolved in a similar way. Supposing a window has just changed from being whole to being broken. Then while the past unbroken state doesn't exist, there does exist a present state of the window having been whole. I am happy to grant this present state to the presentist, but it doesn't affect the argument. For the relevant difference isn't between the window having been whole and the window being broken. For if no one broke the window, there would still have been a difference between the state of the window having been whole and the window being broken. There is always a difference between a state of something having been so and a state of its being so, but this difference isn't the difference that constitutes change.

(Incredible as it may seem to the presentist, when I try to imagine the presentist's world, I imagine an evanescent instantaneous world that therefore doesn't exist long enough for any change to take place. I am well aware that this world includes states like it was the case that the window was whole, but given presentism, these states seem to me to be modal in nature, and akin to the state of it is the case in the Harry Potter universe that magic works, and hence are not appropriate to make the world non-evanescent.)

Probably the presentist's best bet is simply to deny that real difference in my sense is needed for change. All that's needed is that something wasn't so and now is so. But if something's having been not so and its being so doesn't imply a real difference, it's not change, I feel.

Of course, the presentist feels very similarly about the B-theorist's typical at-at theory of change (change is a matter of something's being one way at one time and another way at another time): she feels that what is described isn't really change.

And this, finally, gives us the real upshot of this post. There are interesting disagreements where one side's account of a phenomenon just doesn't seem to be a description of the relevant concept to the other side--it seems to be a change of topic. These disagreements are particularly difficult to make progress in. Compare how the compatibilist's account of freedom just doesn't seem to be a description of freedom to the libertarian.

I don't have a general theory on how to make progress past such disagreement. I do have one thing I do in such cases: I try to find as many things connected with the concept in other areas of philosophy, like epistemology, philosophy of science, ethics and natural theology. And then I see which account does better more generally.


Heath White said...

For what it's worth ... I used to be very sympathetic to A-theory. I believe my intuition was this. Time is REALLY different from space. B-theory seems "static" because there doesn't seem to be a strong distinction between the spatial dimensions and the temporal dimension. (This of course can be a selling point for B-theory.) On B-theory, it seemed like an accident that my conscious experience was ordered earlier/later as opposed to, say, north to south, or that it was temporal at all as opposed to Boethian-eternalist.

I still find these points fairly strong. But I am somewhat sympathetic to the idea that the temporal dimension is just the dimension of causation, and that goes some way to solving the problem, especially if we assume my conscious experience is caused by the world I live in. (This in turn lends itself to a physical explanation of consciousness.) The conscious experience of an uncaused being would quite naturally be non-temporal. Also reflecting on what reality would have to be like for an eternal being to make sense pushed me towards B-theory. (One objection to an eternal God is that such a God cannot know what time it is. B-theory solves this problem nicely.) And relativity theory made a difference, although I would not have found that convincing by itself.

Also, at different points in my career, people that seemed like they knew what they were talking about were A-theorists or B-theorists. I think one should not underestimate such influences.

I bet presentists have a strong sense that change involves time in a way that is way different from space, and they think the non-presentist doesn't give them that. You want change to be a relation between two (as it were unchanging) realities, whereas they think no, there is just one reality, and it changes through time. Change through time seems NOT AT ALL like alterations across space.

Kenny Pearce said...

I've never been able to figure out presentism. It seems like presentists always start by pumping some intuition that I just don't have, and then they end up having to do all kinds of backflips to preserve that intuition. When I took my first logic class, and the professor showed how to translate tensed statements by quantification over times, this just seemed to me to be obviously what I had always meant. After all, what could possibly be meant by 'change' other than that things are one way at one time and a different way at another time?

All that to say, I agree with you: the presentist is the one whose universe doesn't include change.

Michael Gonzalez said...

I know this is an old post, but I have just two quick comments to make about how it appears to me:

1) On B-theory, there is exactly as much "change" between the state of Z at T and the state of Z at T* as there is between the PIECE of Z that is located at spatial coordinate X and the piece of Z that is located at spatial coordinate X1. In other words, imagine a triangle. It is different at the spatial location of its apex than it is at the spatial location of its base. But no one would consider that change has occurred, since this is a static ("at-at") sort of difference. It is precisely the same for the B-theorist with regard to the triangle's state at time T vs. its state at time T*.

2) On presentism, you have said the relevant response but seem to have missed its import: The window actually is broken now and had been whole. That is all anyone ever means by "change". No one is merely pointing out that "unbroken" is different from "broken". They are saying that the window is [I]in fact[/I] broken, and used to be whole.

You imagine the presentist's world as evanescent and instantaneous, but that is not how any presentist is presenting it (no pun intended), not is it the natural, pre-theoretical, commonsense view to which the presentist is appealing. The world is dynamically and constantly in a state of evolution. It is always changing. Even if there are instants, they are instants which carry the baggage of the past and the possibilities/intentions toward the future. There is no "slice of time where the baseball is at coordinate x". There is, instead, the "slice of time where the ball is on its way to the mit, having been thrown by Alice, with a particular trajectory for particular reasons, etc etc etc". And, looked at that way, change is very obvious and very commonsensical on a presentist view...

Alexander R Pruss said...

"On B-theory, there is exactly as much "change" between the state of Z at T and the state of Z at T* as there is between the PIECE of Z that is located at spatial coordinate X and the piece of Z that is located at spatial coordinate X1."

Only if time is exactly the same as space. But nobody thinks time is *exactly* the same as space.

Michael Gonzalez said...

It's hard to see how to make time different in such a way that change means what everyone naturally means by the word "change".... Whereas, for me (which I guess is the point of your original post: or intuitions may differ) there is nothing hard to see about how the window which is broken now has as part of it's present truth that it WAS whole, and so it has undergone change in a robust and intuitive sense.

Alexander R Pruss said...

Heating is making something colder be warmer. The *concept* of heating requires that there be a difference between colder and warmer, but it doesn't require a *particular* story about what the difference is. We now think the story has something to do with the mean kinetic energy of molecules. But it could have turned out that the story would have involved a caloric fluid. The concept of heating is equally compatible with both scientific stories, precisely because it is *a posteriori* that heating is the increase of the mean kinetic energy of molecules.

One could think the same thing about change. Change is a matter of being one way at one *time* and another way at a different *time*. That's all there is to the *concept* of change. The rest is a matter of investigation, both philosophical and scientific, as to what differences of time are (and how they differ from differences of space). But multiple answers to *this* question are equally compatible with the concept of change.

But as I said more recently, I do think the at-at theory doesn't capture everything there is about change.

Michael Gonzalez said...

**Minor epiphany... maybe**... May I suggest that actually the commonsense, universally agreed upon definition of "change" is actually to CEASE being one way and become another? It is true that change always involves being one way at one time and another way later, but that seems derivative on the "ceasing and becoming" definition. Or rather, that is a RESULT of change; not the MEANING of the term. *Consider: If I say that X was in state 1 at T1 and then in state 2 at T2, the most normal thing to say is "then it must have changed at some point". By your definition, that would be a pure re-statement, but everyone seems to think that it is slightly different. A reasonable (and perhaps obvious) conclusion; but not a tautology.

Maybe I'm wrong, but it definitely seems to me to be ever-so-slightly different, even if referring to the very instant before the change and the very instant after the change, the change itself is considered an event which [b]CAUSES IT TO BE THE CASE[/b] that X was in state 1 at T1 but in state 2 at T2....

Alexander R Pruss said...

I don't know if change is explanatory, but it might be, and if so that would be a nice way of capturing an inadequacy in the at-at theory. I think the question is similar to the question whether velocities are explanatory. You could think velocity just *is* the rate of change of position over time. But you could think that velocity is a physical quantity that *explains* why and how the position changes over time.

Michael Gonzalez said...
This comment has been removed by the author.
Michael Gonzalez said...

[edit] Sure, though I think "movement" (which just is a sort of change) is probably a better analogy. Why is this thing no longer located there but instead located here? Because it moved.

I believe that the intuition the presentist is trying to push is that, since all things are 4-dimensionally static on a B-theory view, there is never any change. There is just the 4-d shape of objects (worms or otherwise). Why? Because change means CEASING to be one way and BECOMING another way, whereas nothing ever ceases to be the case from a 4-d standpoint on B-theory.