On his Dangerous Idea blog Victor Reppert quotes an argument that supports a version of the Principle of Sufficient Reason (PSR). When philosophers start going on about possible worlds, I usually catch a whiff of snake oil. Such is the case here. This is the argument:
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)
The argument for PSR3, at least as it is presented here, is gibberish, philoso-babble in its worst form. But really there is no need to worry about it, since there is no reason why any atheist would accept its initial premise, PSR3’. Why should any atheist accept that there is possibly a sufficient reason why some contingent concrete objects exist rather than none at all? What could such a sufficient reason be? It could not itself be a concrete contingent object, since we would immediately have to inquire about the sufficient reason for its existence, and so our question about why there is something rather than nothing remains unanswered. Well, then, if it cannot be a concrete contingent object, then either it is not concrete or it is not contingent. If it is not a concrete object it must be an abstract object like a number or a set. But it is very hard to see how an abstract object could be the sufficient reason for any concrete thing. Could the number seven, for instance, create a quark or a superstring? It therefore must be a concrete non-contingent object. But what does it mean to say that an object is non-contingent? If it is not contingent, it must be necessary. In what sense necessary? Logically necessary? If so, then PSR3’ entails the proposition “Possibly there is a logically necessary concrete object.” But why should any atheist accept that? Why not take it as obvious, as I do, that for every possible concrete object o, there is a possible world in which o does not exist (even if o is omniscient, omnipotent, and morally perfect)?