1. Either something exists or nothing exists.
2. Anything that exists is either caused or uncaused.
3. Anything that is caused has a finite or an infinite causal series.
4. Anything that has a finite causal series has an uncaused first cause.
5. Therefore, either nothing exists, or something exists which is uncaused, or something exists which has an infinite causal series, or something exists which has an uncaused first cause.

If it is the case that nothing exists, then that is an extremely remarkable ‘state of affairs’, since it so strongly seems to be the case that there are things which exist. You and I, for instance, or the letters on this page. Further, if there is something with an infinite causal series that would also be very remarkable. Just ponder it for a moment. How would such a beginningless causal series work? How could there be such an unbroken series of causes, stretching back, or down, forever and ever? But if there is, or has been, some uncaused thing then is this is hardly less remarkable. How could there be something uncaused? What accounts for is (sometime) existence?

Of course, the conclusion of the argument can be avoided by denying one or more of the premises. But go right ahead, for this results in remarkable things also. It would be remarkable if it is false that either something exists or nothing exists. It would be remarkable if it is false that anything that exists is either caused or uncaused. It would be remarkable if it is false that anything that has a finite causal series has an uncaused first cause. And what about denying that the argument is valid? Well, it seems valid to me. But, go right ahead, show me how it is invalid.