Thursday, April 24, 2008

An argument against presentism

Presentism holds that only presently occurring events exist. You and I are watching an exciting game of tennis. Our particular interest is drawn by Federer's next serve which is at a match point. With eager anticipation I speculate about how the serve will go. Federer is serving. You briefly respond to my remark during the serve itself, saying that my speculation doesn't look right. Federer has served and wins the match. We continue disagreeing about the serve for the next fifteen minutes. Such a conversation is perfectly natural.

It seems essential to understanding how the conversation goes that we are all the time talking of the same serve. I claimed before the serve that it was going to be and then continue to maintain that it was a beautiful topspin. You claim that the serve was a poorly executed topspin-slice which only won the game by a fluke.[note 1]

It is difficult, however, for the presentist to maintain that we are talking about the same thing. After all, my initial remark, according to presentism, is about the future existence of a serve (note that on open-future presentism, it is not even yet the case that the serve will exist). Your next remark is about an existing serve. My next one is about a serve having existed. What unifies the topic of these remarks? After all, they are only a disagreement if they concern the same serve.

Moreover, consider the state of affairs that I am claiming to obtain, the state of affairs of the serve being an excellent topspin. Let us suppose I am right. Then it seems I am continually pointing to the same state of affairs throughout the conversation. I am certainly not changing my mind—I am too pigheaded for that. Consider now the truthmaker of my claim.

There are two kinds of presentist views about the truthmakers of claims apparently about past or present events. On a Bigelow kind of view, these truthmakers are presently existing but tensed concrete (i.e., non-abstract) states of affairs. On this view, I am initially claiming the obtaining of the concrete state of affairs of an excellent topspin being about to soon be served. You respond, during the serve, with a denial of the occurrence of the concrete state of affairs of an excellent topspin being presently served. I pigheadedly affirm the obtaining of an excellent topspin having been served. How is there any disagreement here? I first maintain the occurrence of one state of affairs, to which you respond with the denial of the occurrence of a second, and then I respond with an affirmation of the occurrence of a third? It seems plain that according to this kind of presentist we are talking about three different states of affairs, one of which (the one talked about during the serve itself) includes a serve, and the other two of which do not (since there are no past or future serves according to presentism).

Moreover, while the point is most vividly made concerning conversation that straddles the time of the event talked about, the point also can be made in regard to a distant past event. Suppose you and I are discussing the Battle of Waterloo. What makes it be the case that we're talking about the same battle? We can't just be talking of the present state of affairs of there having been such-and-such a battle. For there were many battles in the past. Rather, we're talking of the present state of affairs of there having been a battle x seconds ago. But the x keeps on changing, so the state of affairs we're talking about keeps on changing on us.

The second kind of presentism, ably defended by Merricks, holds that there are no truthmakers for typical past and future tensed propositions. Then my first claim, made before the serve, has no truthmaker. Your denial of the claim, during the serve, is the denial of a claim that in fact does have a truthmaker—the presently occurring serve. And then my subsequent re-affirmation is the re-affirmation of a claim that, again, does not have a truthmaker. Plainly you and I are not talking about the same thing, since there is no truthmaker homogeneity (two propositions are truthmaker-homogeneous iff they both lack truthmakers or they both have truthmakers of the same kind) between what I say and what you deny.


Enigman said...

I'm a Presentist, so for me the past no longer exists, but the reality that is fully present now did used to be different. I don't deny that time exists, or that consequently change is possible. Hypothetically, reality used to involve or include Federer serving that serve, which no longer exists (the way in which events exist is odd anyway though).

But even if the reference to that serve went via Bigelow's three states of affairs, why would referring to it like that have been any odder than, say, referring to a building via three different aspects of it (the first through fog, the last through a camera, but all simultaneously)?

Indeed, even if we naturally refer via B-series conceptions, should even that be any more of a guide to what really exists than, say, our natural reference to coloured objects?

Alexander R Pruss said...

"But even if the reference to that serve went via Bigelow's three states of affairs..."

Two problems here. First, how can there be one serve made reference to in the three cases when in two of the three cases the serve is non-existent? This is not a knock-down argument, since there are stories that can be told about reference to non-existent particulars (e.g., haecceity-based stories), but it's a problem.

Second, the problem is that there seems to be no disagreement between the statements. First I affirm one state of affairs. Then you deny the existence of a different state. Then I affirm a third state of affairs. Where is the disagreement? Maybe there is some hidden incompatibility between what I say and what you say that accounts for the disagreement. But surely there is no need to posit that--the disagreement seems to be there right on the surface.

Beancan Tatterpants said...

I see the bigger problem for Presentism being math. Exactly how long is "the present moment"?

No matter how short the present moment might be, I can conceive of a shorter one by dividing your answer in half - and this patterns continues as we approach infinity.

Therefore, we reach a point where speaking about a certain reference point no longer matters since your uttering of the individual letters in the phrase "top spin" exist in different moments. As soon as you finish sounding out the T, a different moment occurs and you're arbitrarily sounding out a soft O.

And by the principle of splitting that moment in half, the present moment could give way in the middle of pronouncing a T, creating complete discord with speech altogether.

Without a way to successfully measure "the present moment" to define it, it seems problematic to claim that it's the only moment that exists.

Although I wonder what throwing in the world view of someone like Berkeley might do. In such a case, you wouldn't be speaking of the tennis serve, but your perception of the tennis serve. And you would continually use that perception (which exists in your mind) at all times. It erases the need for an outside reference point that exists in concrete time. Your perception somehow endures or perdures through moment to moment so you can speak of it.

And so that you and your friend may come to loggerheads since you're talking about two different things. :)

Enigman said...

If the past is just a way of speaking of the way we were, then since the way we were is no more, the past is no more. But the way we are now is not like an existing substance anyway, but an aspect of it. The aspect goes into the past, we say, meaning only that the existing substances change, like a wave moving over water that remains where it is. Think of the now as a column of water, moving up and down. No water on either side of it; but we can model it as a column of water surrounded by water. The height the column was is the height of an imaginary wave now beyond the column. But it is not that the wave (the serve) existed, and then (for the Presentist) did not. It is that there was only the column of water, changing its height (the serve was never an existing thing, only its time-slices were temporarily properties of existing things). And to ask how long the present is is to presuppose that time exists around or at least throughout the present. The column has no width, but that is not a problem because the space it is in is, for the Presentist, purely imaginary.

Enigman said...

...that is, the now is not infinitely thin; rather, the dimension in which it would be measured does not exist. So the thinness of the now is imaginary. In fact, on Open Theism the now is very fat indeed, so fat that it is, not so much enclosing God, as how God has Being - it is as fat as any (essential, I would say) attribute of God. The now of the (divine) Presentist is a (very) fat now, so fat it includes all that is.

But to return to the serve, suppose you say "That rose; so red," and I say "Yes;" on what are we agreeing? We seem to be agreeing on something, something that is right there on the surface, etc... so, if that sort of thing is a problem, from which one might legitimately deduce one's metaphysics, one might find oneself in a world in which the redness of the roses is painted onto the roses, so to speak (in wonderland, in other words). But such objects are unlikely to make sense except under (divine) Presentism...

Enigman said...

Re reference to the serve, the present serve is the event of the continuant Federer serving, which takes some time (so to speak, as always). There is Federer, fully present, at some stage of the serve (if not after the serve or before it), but where is the serve? Even the present serve does not exist.

But it can be referred to directly because part of it is being instantiated by the state of Federer. Since the unproblematic reference to the present serve is reference to a non-existent serve, reference to non-existent serves is prima facie no more problematic than reference is in general.

What makes reference to non-existent serves reference to the same serve is that the implicit descriptions pick out the same states of Federer. What makes the serve an actual serve is that its component states were states of an actual continuant, Federer.

States change (a sequence of states could be the states of a clock, or some sequence of moments being counted out by an angel) and I can see no problem for the Presentist in the mere fact that continuants have changing states.

Alexander R Pruss said...

How can something be a part if the whole doesn't exist?

Enigman said...

The serve, as a sequence of abstract (uninstantiated) states, existed (hypothetically) as that sequence - Federer's states did so change - but it did not exist (physically) like a presently instantiated property of a continuant. But each of those states did so exist, and so the serve could have been referred to directly via any of them ("this serve" = "a serve-type sequence of states of that continuant that includes this state," perhaps). That, or rather something to which that is an incompetent approximation, is (I conjecture) how.

Cf. does Federer's height exist? When Federer exists it does, being one of his aspects, but does it when Federer does not exist? In a sense, he has no height if he does not exist; so it does not. Yet all the heights he had do not cease to exist, when he does, because they are relatively abstract objects (numbers of inches). When Federer exists, one of them exists (or is instantiated) as none of the others do, and is part of the whole of all of them, since it exists (as a more abstract height) as they all do.

Cf. do numbers exist? Here are three numbers: 1, 2, 3. Therefore numbers exist. But unicorns do not exist, and numbers are much more like unicorns than horses (if we assume, falsely I believe, that unicorns are not rhinos), so numbers do not (or arguably do not) exist. Cf. do elves exist? They only fail to exist physically, so does that mean that the answer is "Yes"? Etc...

Enigman said...

Less appositely, the whole might exist as a work in progress, an impossible ideal, an unobtainable limit, e.g. the natural numbers, if they are potentially infinite. The natural numbers have a relatively crisp definition, so they are a good class of objects, but they may go on and on endlessly, being indefinitely extensible.

So there is a sense in which 1, 2, 3 and so forth exist, but their whole does not. Similarly with sets and proper classes. One might say that sets are those parts of proper classes that do (as proper classes themselves do not) exist.