Saturday, 20 April 2013

The Non-Indexical Core of Presentism is Monism

In recent discussions about temporal ontology, there has been interest in the question of the prospects for a non-indexical, or externalist, formulation of presentism. Some say there are no prospects. Thus Hinchliff (2000):

[A substantive distinction between presentism and eternalism] cannot be formulated in nonindexical terms. That is why I have formulated [presentism] with the aid of the indexical 'presently'.

Others have tried with elaborate means to formulate something which could reasonably be called a non-indexical version of presentism. Matthew Farr, for example, is currently exploring a strategy involving two temporal dimensions. (This note was inspired by a talk he gave at the University of Sydney on 25/3/13 called 'Supertemporal Ontology and the "Triviality" Problem'.)

The issue is obviously interesting, assuming that the question of the meaning of presentism is interesting. One special connection in which it is interesting is this: if there is no non-indexical core of presentism, then perhaps the metaphysical dispute between presentism and non-presentism can be dissolved, on the grounds that presentism is not a distinctive thesis about the structure of reality, but something else (a "view from inside", or something).

I am certainly sympathetic to the idea that the debate in temporal ontology (between presentism, eternalism, the growing block view etc.) is something which should be dissolved or transcended. I seriously doubt that this is a debate about some real subject matter, let alone that it is a debate about some real subject matter where one of the positions is right and the others wrong. I think the confusion here is deep, philosophically important, and deserves to be investigated carefully, not just dismissed. However, I do not think that the idea that the debate cannot be formulated non-indexically is a way to make progress on this, because I think that idea is wrong.

My suggestion here is that we can analyse presentism as the conjunction of two claims, one of which is non-indexical and incompatible with eternalism, growing blockism and shrinking blockism, the other of which is indexical but agreed to by all these parties.

(P) Only the present moment exists.

may be analysed as

(P-conj) Only one moment exists, and this moment exists (where 'this' indicates the present moment).

Call this the conjunction analysis. The non-indexical core of presentism, on this suggestion, is simply the first conjunct: monism about moments (or times, instants, timeslices or whatever).

This non-indexical core is, of course, compatible with strange propositions like:

(S) Only one moment exists, and it is the moment of Napoleon's birth.

But so what? No one believes that, and everyone (presentist, eternalist, growing blockist, shrinking blockist) believes that the present moment exists. Forget the label 'presentism' - look at the conjunction analysis, and it becomes clear that what is really distinctive about this view - i.e. what distinguishes it from other actual contenders - is its monism.


Hinchliff, M. 2000. 'A defense of presentism in a relativistic setting', Philosophy of Science 67, pp. S575-S586.


  1. Doesn't the presentist also believe e.g. that at 9:00 on Thursday, only the moment [9:00 on Thursday] will exist (and, more generally, that at any moment M, only M exists)? That sort of fact isn't entailed by 'only one moment exists, and this moment exists'. It's consistent with the fact that the present moment is the only one presently existing that at some other moment more than one will exist/has existed.

    How about 'for any moment M, M exists at M and only one moment exists at M'?

    1. It's true that what I've called the non-indexical core of presentism doesn't capture the idea that what moment exists changes, nor the idea that there has never been nor will there ever be more than one moment.

      Four-dimensionalists often account for change by saying something like: there is change iff there are two moments with different properties. But, on an ordinary understanding of quantification and ontological commitment, the presentist can't say that.

      A more presentist-friendly formulation is perhaps one involving tense-operators. One idea I had recently for this is, roughly: there is change iff some tensed proposition P (e.g. 'I am sitting') differs in truth-value from some proposition which applies a tense-operator to P (e.g. 'It will be the case that I am sitting').

      Regarding the second idea, that there never has been nor will there ever be more than one moment, your formulation, in quantifying over moments, should perhaps also be recast operatorially: It has always been the case that there is only one moment, and it will always be the case that there is only one moment.

      Of course, the presentist is pressed to give an account of the truthmakers of propositions with tense-operators, or an account of why they do not need (existing) truthmakers.

      Tensed properties are one candidate for such truth-makers. I feel uneasy about this myself - I once said to N.J.J. Smith, and he agreed enthusiastically, that tensed properties seem to contain all the stuff the four dimensionalist has, but put into funny little grey packets. (Anyway, this gets us deep into the debate about the overall viability of presentism.)

      These things about change and there never being more than one moment could certainly be counted as part of what 'presentism' should designate, but I'm still happy to call 'Only one moment exists' the core of it. I don't think it matters much though, if you prefer to say the core has more in it.

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