In the book In Defense of Natural Theology (IVP, 2005), Garrett DeWeese and Joshua Rasmussen wrote an essay entitled “Hume and the Kalam Cosmological Argument.” defend a version of the Principle of Sufficient Reason, which they call PSR3:
PSR3: There is a sufficient reason why some concrete objects exist rather than none at all.
However, they say that PSR3 is rejected by William Rowe on the grounds that it is not self-evident nor a required presumption of scientific inquiry.
However, they think that PSR3 follows from a weaker, modalized version of PSR:
PSR3’: Possibly, there is a sufficient reason why some contingent concrete objects exist as rather than none at all.
They prove this with this argument:
There is a possible world W in which q is true and q explains p.
p is contingently true and there is no explanation of p. (Assumption for indirect proof).
There is a possible world W in which (p and “there is no explanation of p”) is true, and there in which q is true and q explains (p and “there is no explanation of p). (from 1 and 2)
In W, q explains p, (from 3 and the distributivity of explanation over conjunction).
Therefore in W, p both has, and does not have an explanation.
It is not the case that p is contingently true and there is no explanation of p.
Therefore, it is not the case that, for any proposition p, p is contingently true and there is no explanation of p. (from 6)
5 comments:
Hi Victor,
It seems to me that the only way to accept PSR3' here is to reject origin essentialism. Thus, suppose we've got our hands on a universe, and suppose we give it a Kripkean baptism: (pointing to the universe) "Let *that* be called 'Uni'. 'Uni' is now a kripkean rigid designator -- it refers to *that* universe in all possible worlds in which it exists.
So now we have a way to hold Uni fixed, so we can start considering modal claims about *it*. Well, there are two relevant possibilities for us to consider here: (i) Uni has its origin in the causal power of a divine being,and (ii) Uni has no origin. If (i), then, by origin essentialism, this is an essential property of Uni, in which case there is no possible world in which Uni lacks such an origin.
If (ii), then it lacks an origin in the causal activity of a divine being, and so *this* fact about it is essential to it, in which case there is no possible world in which it has an origin in the causal activity of a divine being.
The moral, then, is that if we accept origin essentialism like good kripkeans, then whether a universe has an explanation in terms of a divine being doesn't vary from world to world. But if so, then PSR3' is of no help until we know *beforehand* whether our universe has its causal origin in the causal activity of a divine being. But if we already know *that*, then the contingency argument would be superfluous.
Of course, one could always reject origin essentialism, or restrict its scope in a way favorable to the argument, but then the audience for the argument shrinks considerably, I should think.
Best,
EA
To my mind this argument falls down at (3):
'There is a possible world W in which (p and “there is no explanation of p”) is true, and there in which q is true and q explains (p and “there is no explanation of p). (from 1 and 2)'
The argument could simply be reversed to show that this is incoherent, and doesn't represent a possible world at all. Indeed, if we accept the "distributivity of explanation over conjunction" it seems obvious that we can't coherently assert:
(a) P
(b) There is no explanation of P
(c) There is an explanation for the truth of ((a) & (b)).
This triad is incoherent, in all possible worlds at least one of them is false. Since, ex-hypothesi, (a) and (b) are both true in W, (c) must be false in W, and therefore premise (3), quoted in italics above, is false.
There are interpretations of (3) which make it seem true, but then I think we'll either be equivocating on "explanation" or using senses in which "explanation" doesn't distribute.
Steve
This is Keith Parsons' response to this argument for this form of PSR, for which I have some sympathy. That is I get a little suspicious when we get an innocent seeming possibility claim which supports that the claim is actually true.
http://secularoutpost.blogspot.com/2007/08/possible-worlds-and-psr.html
Looks like some intelligent bloggers post here. Yeah, origin essentialism poses a problem for weakened versions of PSR (van Inwagen first made this evident to me). I would argue that origin essentialism is false, but that's another argument... Anyway, I'm a little uneasy about our proof of PSR3' (notice we don't prove PSR3' but a slightly different principle.) But I've been developing a much more sphisticated and complete argument. I'll email it to Victor and let him post any remarks on it if he wants to...
~Josh Rasmussen
From Plantinga's review of Dawkins '... the theist neither wants nor needs an ultimate explanation of personhood, or thinking, or mind.'
So no 'sufficient reasons' are needed for Dawkins-refuters.
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