Is Presentism true(-making apt)?

Here’s an argument against presentism from the intuitively plausible principle that for any truth, there must be a truth-maker which makes a difference. Although I’m assuming a correspondence theory of truth, I don’t mind flirting with the idea that other theories of truth could adopt some truth-making principle and carry on with my argument keeping everything else the same. What I mean, here, by making a difference is something like this: if there is a possible world W1, in which T1 is true, and M1 is T1‘s truthmaker, then there is no possible world W2 which is maximally close to W1 in all respects save for that M1 (or its equivalent M2)[1] is unavailable (so, similar mutatis mutandis), at which T1 (or its equivalent T2) is true. I will bracket concerns about whether truths are multiply-realizable in the sense that any particular truth Tn might have any of a set of realizers {M1, M2, M3… Mn}, and I will, therefore, dodge questions about over-determinated truth-values and related concerns; I only note in passing that I don’t think much of these concerns, but I want to avoid them because I also haven’t thought much about these concerns.

Suffice it to say that by T1 having a truth-maker in M1, I mean that M1 is the reason T1 is true.[2] Now, consider the world as it looks through the eyes of a presentist. The presentist believes that the set of all things which exist, and the set of all things which exists now, are identical. There is no thing which both exists, and does not exist presently. Only the sum of all truths which are true ‘right now’ are true at all (this may be thought to be an unfair characterization, since the presentist may still believe that necessary truths have timeless entities, such as abstract objects, as their truth-makers, but I think this is contrary to the letter, if not the spirit, of presentism; for the strict presentist, only that which is present exists).

Now, what, on presentism, can account for the fact that we can make true statements about the past (let alone the future)? There is, presumably, some truth-making ingredient which presently exists which can make true statements about the past true. However, consider the classical problem in epistemology of the unverifiability of the reality of the past. As Bertrand Russell put it in his famous Problems of Philosophy, our knowledge of the past is based not on sense-experience (which would make it empirical in the strictest sense), but on our acquaintance with our own memory. We must, he insists, be able to have knowledge by acquaintance with things other than sense-experience, or else we would not be able to know that the past was real:

“But if [sense-data] were the sole example [of the things with which we are acquainted], our knowledge would be very much more restricted than it is. We should only know what is now present to our senses: we could not know anything about the past–not even that there was a past…
This immediate knowledge by memory is the source of all our knowledge concerning the past: without it, there could be no knowledge of the past by inference, since we should never know that there was anything past to be inferred.”[3]

The point here is that skepticism about the reliability of our memory will lead to skepticism about the very reality of the past, a worry which no amount of empirical investigation can alleviate. Suppose, for the sake of argument, that the whole world popped into existence moments ago with the appearance of age (e.g., light travelling to your retinas with the appearance of having come from stars (light-years away), memories of the first half of the conversation you may now be in, memories of having read the opening paragraph of this post, etc.). How would the world look any different from how it would have looked if it had had a past (and, let’s assume, precisely that past in which the evidence leads us to believe)? There seems to be no difference between the two. The worlds look empirically identical.

You might (quite rightly) think that these possible worlds could be metaphysically differentiated, but how could we articulate the metaphysical distinction on presentism? We cannot just say that only one of the worlds has the property of having a past, for whatever that amounts to on presentism will, it seems, be metaphysically indistinguishable from the property of having the appearance of having a past! Where, on the present ‘slice’ of the universe (whatever shape that takes), cosmos, and/or noumenal world can we locate a truth-maker for past-tense truths which would not have been there if the world had merely popped into existence moments ago preloaded with all the appearances of age? If there is no way to articulate a difference, then we might have on hand a good reason to be skeptical of presentism (or else, I suppose, skeptical of truth-making accounts of truth, but I take it as nearly incontestable that presentism is less intuitively secure than the generic truth-making account of truth). Maybe I’m mistaken, but I am under the spell of a powerful suspicion that the metaphysics of presentism makes no room for the kind of truth-maker I’m looking for.

But: perhaps there is a problem with the question itself. The presentist might insist that they take issue with the grammar of this objection, since it seems as though it assumes the reality of the past. The presentist may insist that on presentism there is no metaphysical difference between the possible world ‘with a real past’ and the possible world ‘with an apparent past’ precisely because there is no difference (i.e., simpliciter). The question becomes a pseudo-question, and the presentist follows the dance-moves of the positivist around the issue. This, however, seems to me to be an at least equally damning flaw in presentism as the lack of a truth-maker would be; if the presentist cannot make room for the meaningfulness of a distinction we all know very well to be meaningful then we should treat presentism with the same[4] disdain with which we treat logical positivism. If they do not make room for the semantic difference then they will either be violating the law of excluded middle, or they will be denying the meaningfulness of propositions we all know to be perfectly intelligible.

[1] I’m not sure if this comment, along with the one shortly to follow, is entirely appropriate here. I suspect that it may depend on one’s theory of reference across possible worlds. Nevertheless, I think my meaning is clear enough for the purposes of this post.

[2] Depending on how we cash out ‘reason’ here, this might be enough to avoid the difficulties I gestured towards above.

[3] Bertrand Russell, The Problems of Philosophy, (OUP: Oxford, 2001), 21.

[4] If not the same, on account of logical positivism’s being self-referentially incoherent (a flaw which we have yet to show presentism to have earned for itself), then at least a similar disdain. One might even say, a disdain so similar that the difference cannot be verified.

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