Hans Kung divides the a posteriori arguments for God’s existence into those based on the principle of causality and those based on the principle of finality, and then makes the same basic objection to both: they get “lost in the incomprehensible infinite, in which it is by no means certain if it is fulness or emptiness, God or nothingness”. Kung does not develop this argument, but he might have something like this in mind:
1.) Real being, at least for us, is categorical; God is not in a category. If we visualize the category as, say, a circle enclosing things, then we can certainly imagine the supra-categorical as what is in the space outside of the circle. But to take it in this way would identify being and nothing. This image is not meant to be taken as the basic argument, but as suggesting it – aren’t all of our concepts categorical, even if (as happens with the analogous) they are found in more than one category? True, this opinion does face a strong challenge from the fact that there is a sharp division between knowing what something is and knowing that it is, and that the cosmological argument claims to give knowledge of the latter and not of the former. But even then St. Thomas himself has a hard time making a sharp distinction between these two sorts of knowing, and if the distinction only amounts to the difference between, say, the pronoun (that) and the noun (what) then it will not be robust enough to survive Kung’s objection.
2.) Act is a principle as opposed to a being, Pure Act is not. The whole development of the distinction between potency and act was to answer a question about the possibility of motion, and in this context we must take act and potency as principles as opposed to things. But it is not clear that there is any sense to making a real division of such a principle, or even if this is possible: a two-dimensional plane is a real principle of a three-dimensional solid, like a door, but one can’t sand down the door till it’s a two-dimensional plane.Is Pure Act to be taken as a being, since it is Act; or as nothing since, given that it has no potency, there is also no subject of this pure actuality?
To face the obvious objection to both: our ideas of cause and of analogy cannot be really separated from the problems of being and actuality. It is no talisman against the categorical nature of thought, or the fact that act is a principle and not a thing, to invoke the idea that we can name things analogously or discover some things to be causes.
I disagree with Kung, but I very much value his argument: I think points us to seeing that thought is essentially supracategorical (though, to be sure, we would simply beg the question if we said thought was supracategorical because it can know God by a cosmological argument). To anticipate, all intellection – even my own intellection – is being’s reflection on itself. Thought only becomes categorical when it is accessed by a psycho-physical entity (like me) that is really distinct from it; or, said another way, thought is categorical from a feature outside of thought itself – and thought is only what is to the extent that being reflects on itself.
And yes, I have a lot of work to do to avoid all the obvious objections.