t being, it follows that there must be some self-existing being. So far, it seems that the Cosmological Argument indeed proves the existence of a self-existing being. Both of its premises have been shown to be true, so it passes the premise test, and also, the conclusion follows from the premises -- it passes the inference test. But has anything been overlooked? Yes, it has. The only way that premise (1) and (2) can be true is if the Principle of Sufficient Reason is also true. The question, of course, is whether or not PSR is true. What reasons for its truth could we offer? Rowe suggests two traditional reasons offered in favor of accepting the truth of PSR. The first reason is that "some have held that PSR is (or can be) known intuitively to be true" (Rowe 29). Just as we know that two plus two equals four is true, the defender of PSR claims that the same sort of thing is true about PSR. Once PSR is understood, the understanding in itself reveals that it is true and must be true. The problem with the first defense of PSR is that while everyone who understands 2+2 knows that it does and must equal 4, very few people who reflect on PSR find that it must be true, "and some even claim that the principle is false" (Rowe 29). Why couldn't the world be such that there were things and positive facts that had no explanation? The second reason traditionally offered for defending PSR "is by claiming that although it is not known to be true, it is, nevertheless, a presupposition of reason, a basic assumption that rational people make" (Rowe 29). The defender of PSR suggests that all of us presuppose that PSR is true, and that we couldn't engage in our everyday activity if we took seriously the possibility that it might be false. The problem with this second defense of PSR is that it even if it were true that we all presuppose PSR to be true, that wouldn't show that it was true. "Even if PSR is a presupposition we all share, the...
