Four arguments that there must be concrete entities

An entity is concrete provided that it possibly causes something. I claim that it is necessary that there is at least one concrete entity.

Argument A:

1. The causal theory of possibility is true.
2. So, necessarily there is at least one concrete entity.

Argument B:

3. Necessarily, if there is time (respectively: space, spacetime, laws), there are concreta.
4. Necessarily, there is time (respectively: space, spacetime, laws).
5. So, etc.

Argument C:

6. Every possible fundamental fact can be reasonably believed (respectively: known).
7. Nobody can reasonably believe (respectively: know) there are no concreta.
8. Necessarily, if there are no concreta, then that there are no concreta is a fundamental fact.
9. So, etc.

Argument D:

10. Necessarily, if there is nothing concrete, the only fundamental contingent fact is that there is nothing concrete.
11. Necessarily, some fundamental contingent fact has a potential explanation.
12. Necessarily, that there is nothing concrete has no potential explanation.
13. So, etc.

And since, plausibly (though controversially),

14. If it necessary that there is a concrete entity, there is a necessary concrete being,

it follows that there is a necessary concrete being. And this some call God. :-)