I cannot leave this argument alone.  Every time I sit down to write about the teleological argument for the existence of God (the argument from design), my thoughts turn to the cosmological argument instead.  Here is my latest effort to reduce the argument to its essence.

There are only four possible explanations for the existence of the universe:

1. The universe is past-eternal;
2. The universe had an uncaused beginning;
3. The universe was caused by a caused cause; or
4. The universe was caused by an uncaused cause.

We can eliminate the first three explanations.

If the universe is past-eternal, then it did not have a beginning.  If so, then it did not have a cause, but just is.  God may or may not exist, but an uncaused universe does not require it.

Empirical science has shown, however, that the universe did have a beginning.  This leads to two more possible explanations for its existence: either it had a caused beginning, or it had an uncaused beginning.  If the universe had an uncaused beginning, then God may or may not exist, but as noted above, an uncaused universe does not require it.

But an uncaused beginning is unlikely because it would violate the laws of cause and effect.  At the very least, it would seem to do so: there is no plausible basis for maintaining that the universe could have had an uncaused beginning. 

The universe, then, must have had a caused beginning.  If so, then again there are two possible explanations for its existence: either the cause itself had a beginning and hence a cause, or the cause itself did not have a cause and hence was past-eternal.

A caused cause is merely one element in an infinite series, unless the series itself has a beginning; and it can only begin with an uncaused cause.  An actual infinite series is impossible and absurd.  Therefore the series of causes must “end” (begin) with an uncaused cause, which uncaused cause must be past-eternal.

(Every caused universe is past-finite and every past-finite universe which can be actualized is caused.  Every uncaused universe which can be actualized is past-eternal and every past-eternal universe is uncaused.)

Thus three of the four possible explanations for the existence of the universe have been excluded: a past-eternal universe; an uncaused beginning; and a beginning brought about by an infinite series of caused causes.  The remaining explanation, that the universe was brought into being by an uncaused, past-infinite cause, must be true.