Thursday, July 12, 2007

Some discussion of the KCA

In a previous discussion of the Kalam cosmological argument an anonymous interlocutor wrote that physicists really don't use the idea of cause and effect, and then presented this explanation.

(To avoid confusion I should clarify again that "cause and effect" is a term used in physics as a synonym for "determinism". Classical physics is deterministic, quantum physics is not. So "cause and effect" is routinely mentioned (as a metaphor) in the context of classical physics, but has dropped out of quantum physics. "Causes" and "effects", however, play no role in the equations of classical or quantum physics. And for good reason: it is notoriously difficult to define "causes" and "effects" in any given situation.)

OK, that may be. But I would think that even in physics physicists would be committed to some version of the causal principle; that is, at least believe in some weakened version of the principle of sufficient reason. Let me quote myself from an old post on PSRs.:

We need explanatory principles, or what in philosophy are called principles of sufficient reason, in order to justify the claim that the universe needs something other than itself to explain it.PSR1: For every contingent fact F some other fact F' obtains such that, given F', F must obtain.This principle is incompatible with classical theism, for reasons which are similar to the ones Steven mentioned. It is a contingent fact that God freely chose to create a universe, according to classical theism. Or, if God had chosen to exist alone, that would be contingent.So PSR needs to be revised. Wainwright offers some alternatives:PSR2: There is a sufficient reason for the existence of every contingent being.This doesn't entail tha there has to be an explanation of every property of that being, just the existence of the being. So, for example, that being freely choosing to do something can be fully nd completely contingent.PSR3: Every contingent fact that requires a sufficient reason has one.A contingent fact "requires" a sufficient reason if and only if 1) it is logically possible for it to have a sufficient reason and 2) it is unintelligible if it doesn't have one.PSR4: There is at least some reason for every contingent fact.I have seen this referred to as the principle of necessary reason, for every contingent fact there are necessary conditions for it.Wainwright goes on:"The weaker principles are strong enough to generate the conclusion that contingent being is caused by a self-exisent being."The upshot of Wainwright's subsequent discussion is that at least PSR4 is supported by the success of human inquiry, and that therefore the weaker forms of PSR are more plausible than their denials. Hence, he does find some legitimacy in forms of the cosmological argument that use some of the weaker versions of PSR4, and he thinks they do lend significant support to the claim that the physical universe depends on something other than itself, which is self-existent.

Now it looks like any of these principles will do the work necessary to support the causal principle of the KCA. Therefore a denial of the very strong sense of "cause and effect" that physicists might have in mind doesn't mean that they don't believe in, say, Wainwright's PSR4. And PSR4 is all William Lane Craig needs.