Hi Mark,

Quick remarks for now:

I know of at least some presentists (such as William Lane Craig) who would simply reject the idea of truth makers. He would ask something like "What makes a number part of reality, what makes 1+1=2 true?" It seems that though their is a kind of correspondence between realtiy and mathematics, there is no specific temporal object that we can point to that makes them true. So the requirement that there be presently existing truth makers would be, on his view, just misguided.

You've confused truthmaking with reference in this paragraph. For instance, the truthbearing statement "There are no unicorns" is made true by the totality of horse-like animals, none of which have horns. Craig argues against Quine's use of reference in first-order predicate logic for making ontological commitments, not against truthmaking.[1]

As for what constitutes the duration of the now, that seems a slightly muddled objection. "The Present" would just be whatever is real at a given moment, what we experience. When you ask how we can identify it, whether in seconds, weeks, years, or whatever, that's an epistemological question rather than a metaphysical/ontological one. The presentist feels no need to give an exact account of what measurement of time constitutes the present because our ability to identify it precisely doesn't effect the reality of the situation. There's perhaps a parallel here with the responses to some of Zeno's paradoxes.

It's not an epistemological objection. It follows from the definition of presentism that the presentist is committed to a present moment that exists, and that the past and future do not. That's an ontological point.

Also, most presentists would that the attractiveness of their position is in large part due to the failure of others. Eternalism seems to give no explanation for the passing of time or why change is possible, for example.

As I partly pointed out before, the growing block theory accounts for both of those while avoiding the objections I made.

In any case, the thrust of the post is that presentism has problems, not that the other views don't.


[1]Incidentally, I agree with Craig on his point concerning Quine's canonical language. The problem is that so has everyone that has made the indispensability argument for mathematical realism since Putnam in the 1970s.

Strictly speaking that last statement blurs Eternalism together with the B-Theory. What is wanted is a theory which preserves the privileged phenomenological and ontological status of the present - it doesn't detract from the theory if the past and future have some ontological status.

John West wrote:

If they don't, then you've turned us into philosophical robots and admitted determinism.

That's true though one need not consider that a defeating objection to Presentism since one could say the same for the B-Theory. Of course one would need other reasons to hold to Presentism e.g. impossibility of eliminating tense et cetera et cetera.

Last edited by DanielCC (9/15/2015 5:55 pm)

John West wrote:

DanielCC wrote:

That's true though one need not consider that a defeating objection to Presentism since one could say the same for the B-Theory. Of course one would need other reasons to hold to Presentism e.g. impossibility of eliminating tense et cetera et cetera.

The growing block theory, however, has no such problem and avoids the objections.

We wouldn't be able to pretend presentism really upholds our common sense intuitions anymore, either. 

That's true (which is why I added the qualifier about additional reasons such as the impossibility of implying tensed translations). I suppose the presentism can claim that his/her theory upholds at least one of our intuitions whilst the Eternalist violates two (though this only holds for the B-theoretical Eternalist).

One point which came up earlier though: does the under-determination take on the truthmaker problem have any advantages that the 'classic' truthmaker problem lacks? I mean the classic problem i.e. what functions as the truthmaker for propositions regarding the past and future bites deeper in that it causes problems for both growing and shrinking block theories.
 

Last edited by DanielCC (9/15/2015 5:51 pm)

John West wrote:

You've confused truthmaking with reference in this paragraph. For instance, the truthbearing statement "There are no unicorns" is made true by the totality of horse-like animals, none of which have horns. Craig argues against Quine's use of reference in first-order predicate logic for making ontological commitments, not against truthmaking.

Er, I don’t know anything about Craig on Quine, but I am indeed talking about truth makers not referents. Originally writing on counter-factual knowledge, he touches on this subject writing:
 
 

William Lane Craig wrote:

“[Certain] abstract entities do not stand in causal relations. This invalidates at a single swoop the crude construal of the grounding objection expressed in Robert Adam’s demand ‘Who or what does cause them [counterfactuals of creaturely freedom] to be true?’ The question is inept because the relation between a proposition and its truth-maker is not a causal relation…. [Past tense statements] about persons who no longer or do not yet exist and so cannot have such persons among their truth-makers… reveal just how naïve an understanding grounding objector have to the notion of truth-makers. For if these statements have truth-makers, their truth-makers are not physical objects out there in the world but are abstract entities like state of affairs or fact.”

(Sorry it’s a little chopped up. I wanted to avoid a mass of text. The full text is in Divine Knowledge: Four Views)
 

John West wrote:

It's not an epistemological objection. It follows from the definition of presentism that the presentist is committed to a present moment that exists, and that the past and future do not. That's an ontological point.

You’re definitely right that that part of the objection is ontological. But your question was about different measurements of ‘now’, saying “ How do we choose one over the other?” which strikes me as a question about how we can determine or know what counts as the present (i.e. epistemological). I think the presentist would be happy to concede that it’s a difficult question, but that our knowledge of what constitutes ‘now’ isn’t necessary for saying there is a ‘now’. After all, sunset is a continuous movement, but that doesn’t mean I can’t tell you when it’s day or when it’s night, or that there is a moment when one transitions to the other. Are gradients all one color because I can’t specify precisely the point at which one color begins and the other ends?
Also, doesn’t the objection work against B theorists and growing-block theory as well? Regardless of your view, you (presumably) believe that there is a difference at least in perspective between the present, past, and future. But you seem to be suggesting that no one can believe in the present if they can’t account precisely for what ‘counts’ as now? I’m unsure that the presentist is in any different position from other theories in that regard.

John West wrote:

I don't think it has any particular advantage or drawback though. It can be reversed for future tense truthmakers, though only theists trying to deal with the problem of God and future contingents would think they need truthmakers for future tense statements.

Okay, I was asking primarily because it lets block theories off easy whilst the other doesn't.
 
As to the problem of future tense truthmakers only being a worry for theists, o contraire, look back a few paragraphs in a certain book which also uses that Othello quote in the context of Presentist problems.

Last edited by DanielCC (9/16/2015 9:28 am)