Notes for Class Nineteen: Philosophy of Religion II

I. The Cosmological Argument (especially as developed by Thomas Aquinas): This argument is based on observation of the universe (the cosmos); as such, it is an a posteriori kind of argument. It claims that if every individual thing or event has a cause for why it is as it is and why it changes as it does. Each thing or event depends on (or is "contingent" on) some other thing or event to account for why it exists or happens. Without a cause, nothing would exist or be intelligible. If there is no ultimate cause of a thing or explanation for why something exists--that is, if the causal sequence is endless or infinite--then nothing would ever happen or be intelligible here and now. But things do happen here and now. So there must be some ultimate cause which itself is not caused by anything else, and that cause is God.

Another way to put this: just as each thing or event depends on something else to account for its existence, so also the whole order of things (the universe) must itself depend on something else to account for its existence. Otherwise, there would be an infinite regress (and endless chain of causes causing causes) and thus nothing to account for why there is a universe at all. That other thing (God) doesn't depend on anything for his existence: his existence is called "necessary."

Notice: Aquinas' rejection of an infinite sequence of causes does not apply to the horizontal sequence of causes in history, but rather to the vertical sequence of intelligibility in terms of which some merely possible thing is understandable as actual right now. That is, it is possible that the universe has existed eternally and never had a precise moment when it was created. If that is the case, then the cosmological argument cannot assume an ultimate beginning to history. Rather, in order to account for something's existence here and now--either things in the universe or the universe as a totality--we have to think in terms of a vertical (ontological) terminus or end of causes. In order to account for the existence of anything in the universe right now , we have to assume that other things exist right now , and those things can only exist if other things exist right now . This sequence cannot go on indefinitely because there would never be something that ultimately accounts for things existing right now . But since things do exist right now , there must be such a cause which does not depend on anything else for its existence: that is, it must exist necessarily rather than contingently ; and that cause is God.

II. Hume's Criticisms of the Cosmological Argument

(a) There is no a priori reason to believe that everything has a cause or a reason by means of which it is explained or understood. And no set of observations can establish a posteriori the truth of the causal principle (viz., the principle that everything has a cause).
(b) The argument commits what is called the fallacy of composition: it assumes that a characteristic of parts of a thing is also a characteristic of the whole thing. The fact that members of a team had biological births does not mean that the team itself had a biological birth. Likewise, the fact that each thing in the universe has a cause does not mean that the universe in its entirety has a cause. Speaking about causes makes sense only in regard to things in the world, not the world as a totality.
(c) If God is the cause of the universe, then what is the cause of God? If God is his own cause, then why can't the universe itself be its own cause? Perhaps the universe has itself existed forever and needs no cause other than simply being what it is (as is said supposedly of God).
(d) Besides, why does the existence of anything have to have an ulitmate reason in terms of which it is intelligible? Why not accept the possibility that things in the universe are caused by other things, and that the sequence of causes has no particular beginning: it simply goes on endlessly, indefinitely, in what is called an "infinite regress"? If thinking this means that things are ultimately unintelligible, so be it. Only the human inclination to think that everything is intelligible requires us to assume an end to the explanation.
(e) Finally, even if we were to accept the argument that the universe has a cause, that would not prove that God is infinite, good, caring, etc. Since the universe is finite, it would prove only that its creator would have to be powerful and wise enough to create it, but not infinitely powerful, wise, or good. Likewise, it would prove only that God is a cause of things who might not care at all about his creation.

Hume's objections to the cosmological argument are not intended to prove that there is no God. They are intended to show merely that the argument does not provide any justified reason to believe in God. That is, the result of Hume's critique is not atheism (the denial that God exists ) as much as agnosticism (the claim that we don't know whether God exists or not ).