The Modal Third Way... Yet Again

Recently I've been trying to reformulate the Modal Third Way (MTW) in a more popular, and easily accessible, manner. Here's what I have so far:

1. Something has always existed.
2. Whatever exists is either temporally necessary or temporally contingent.
3. It is possible that all contingent beings collectively fail to exist at some past time.
4. It is necessarily the case that possible truths are explicable.
5. It is necessarily the case that something is explicable only if something exists.
6. Therefore, a temporally necessary being exists.

Let's take a look at each premise.

1. Something has always existed.

This is true in light of the metaphysical principle that being cannot arise from non-being. If there were a past time in which nothing existed, then nothing would exist in the present, which is clearly false.


2. Whatever exists is either temporally necessary or temporally contingent.

This premise is true via the law of excluded middle. A being can either exist at all times, or else possibly fail to exist at some time.

3. It is possible that all temporally contingent beings collectively fail to exist at some past time.

No logical law I'm aware of would prevent the possibility of the totality of temporally contingent beings from failing to exist at some time in the past. Here we are appealing to possible worlds.

4. It is necessarily the case that possible truths are explicable.

Even assuming that X has no explanation in the actual world, it is perfectly reasonable to conclude that X has an explanation in some possible world.

5. It is necessarily the case that something is explicable only if something exists.

Let's assume the opposite of this premise - namely, that something can be explicable even if nothing exists. If this were true, what is explaining it? Presumably nothing, but nothing explains nothing at all! Hence, something must exist in order for something to be explicable.

If, however, there are no temporally contingent beings at this past time, it follows that the only being that is capable of explaining this is a temporally necessary being. As a result, our conclusion is justified:

6. Therefore, a temporally necessary being exists.