In browsing Wikipedia for some quick facts about something else, I came across this summary of Mortimer Adler’s rather more sophisticated version of the cosmological argument for the existence of God:
In his 1981 book “How to Think About God”, Adler attempts to demonstrate God as the exnihilator of the cosmos. The steps taken to demonstrate this are as follows:
1. The existence of an effect requiring the concurrent existence and action of an efficient cause implies the existence and action of that cause
2. The cosmos as a whole exists
3. The existence of the cosmos as a whole is radically contingent (meaning that it needs an efficient cause of its continuing existence to preserve it in being, and prevent it from being annihilated, or reduced to nothing)
4. If the cosmos needs an efficient cause of its continuing existence, then that cause must be a supernatural being, supernatural in its action, and one the existence of which is uncaused, in other words, the Supreme Being, or God
Two of the four premises, the first and the last, appear to be true with certitude. The second is true beyond a reasonable doubt. If the one remaining premise, the third, is also true beyond a reasonable doubt, then we can conclude beyond a reasonable doubt that God exists and acts to sustain the cosmos in existence.
The reason we can conceive the cosmos as being radically rather than superficially contingent is due to the fact that the cosmos which now exists is only one of many possible universes that might have in fact existed in the past, and might still exist in the future. This is not to say that any cosmos other than this one ever did exist in the past, or ever will exist in the future. It is not necessary to go that far in order to say that other universes might have existed in the past and might exist in the future. If other universes are possible, than this one also is merely possible, not necessary. . . .
The next step in the argument is the crucial one. It consists in saying that whatever might have been otherwise in shape or structure is something that also might not exist at all. That which cannot be otherwise also cannot not exist; and conversely, what necessarily exists can not be otherwise than it is. Therefore, a cosmos which can be otherwise is one that also cannot be; and conversely, a cosmos that is capable of not existing at all is one that can be otherwise than it now is.
Applying this insight to the fact that the existing cosmos is merely one of a plurality of possible universes, we come to the conclusion that the cosmos, radically contingent in existence, would not exist at all were its existence not caused. A merely possible cosmos cannot be an uncaused cosmos. A cosmos that is radically contingent in existence, and needs a cause of that existence, needs a supernatural cause, one that exists and acts to exnihilate this merely possible cosmos, thus preventing the realization of what is always possible for merely a possible cosmos, namely, its absolute non-existence or reduction to nothingness. . . .
Adler stressed that even with this conclusion, God’s existence cannot be proven or demonstrated, but only established as true beyond a reasonable doubt. However, in a recent re-review of the argument, John Cramer concluded that recent developments in cosmology appear to converge with and support Adler’s argument, and that in light of such theories as the multiverse, the argument is no worse for the wear and may, indeed, now be judged somewhat more probable than it was originally.
It’s interesting that the contingency of the universe–that it might be otherwise than what it is–is a key to the argument. Otherwise, one could argue that the universe itself is necessary and self-existing.