Here's a question I'm toying with: Can an omnipotent being commit suicide? It seems to me that it could, at least in one sense:
1. If God were to attempt to commit suicide, he would (or might) succeed.
Richard Swinburne seems to agree (cf. his The Coherence of Theism). But if that's right, then it seems to me that no being -- not even a theistic God -- could be inherently indestructible. But if not, then there can be no being that is inherently metaphysically necessary.
Here's a half-baked objection and reply:
Objection: A theistic god is by definition essentially morally perfect. Therefore, while God could commit suicide (in virtue of his essential omnipotence), there is no possible world in which he would do so (in virtue of his essential moral perfection). The objection therefore depends on the thesis that there are non-trivially true counterpossibles, viz., (1). But there are no non-trivially true counterpossibles; so, the objection fails.
Reply: I disagree. First, I seriously doubt that moral perfection precludes suicide. But more importantly, I think there are non-trivially true counterpossibles (e.g., (1)). But at the very least, such a criticism is controversial, as accounts of non-trivially true counterpossibles are all the rage at the moment, and many philosophers who study such things (theist and non-theist alike, fwiw) accept the existence of non-trivially true counterpossibles. As such, one would like to see a good reason to think that all such accounts are bound to fail before one accepts the objection. Pending a case, (1) seems to indicate that while there may be something intrinsic to God's nature qua morally perfect being that prevents his non-existence (via suicide), there is nothing intrinsic to God's nature qua aseity, considered in itself, that prevents his non-existence. For given God's omnipotence, it seems to follow that he can annihilate himself. But if that's right, then it casts doubt on the thesis that a substance (e.g., God), qua type of substance, could be metaphysically necessary merely in virtue of its self-existence. Or in other words, the "stuff" of God's being, so to speak, isn't inherently indestructible. And if not, it's not inherently metaphysically necessary.