Scott wrote:

Is "act of existence" identical to "existence," or not? If it is, then something's essence being identical with its "act of existence" is the same as its being identical with existence itself. If not, then it isn't; its essence, contra hypothesis, wouldn't be existence itself but an act thereof. You seem to be trying to have it both ways.

(I don't think "existence" is identical with "act of existence," by the way; it just doesn't matter to my present point.)

But isn't the hypothesis being considered precisely about a being whose essence is identical to its existence? If so, then I don't see how I'm "trying to have it both ways".

Scott wrote:

As far as I can see we don't have to do any such thing, but if you think you have a counterexample, we can have a look at it. In general, though, distinctions are based on differences, not sheer numerical non-identity. I have one cat, not two cats that just happen to be composed of the same matter and occupy the same space.

I'm worried about a vicious regress here. If Feser is right in saying that two distinct beings need something that differentiates them - call it a 'differentiator' - then wouldn't the distinct differentiators of those two beings need their own differentiators?

Scott wrote:

Okay, then let's consider your proposed alternative directly. How could it be that the essence of X was identical with the act that brought X into existence? If X's essence were an act, wouldn't X already have be "in act," and therefore exist, in order to bring itself into existence?

Hmm, I'm not sure I understand. If a being's essence is identical to its existence, then one would think that it is the kind of being that cannot be brought into existence.

Scott wrote:

There's more than one way to avoid such a regress without tumbling into bruteness, I should think, but let's look briefly at one of them. Suppose there are two molecules of hydrogen, completely identical in every respect save for their spatial locations, so that they're differentiated only by those locations. Do those locations themselves need something further to differentiate them? I would say not; their difference is already part of their being two spatial locations in the first place. Is their difference merely "brute"? Again I would say not; to me it seems entirely intelligible in itself and not in need of any further explication. The difference between this spatial location and that one is that this one's here and that one's there. What could be clearer?

Of course I haven't tried to give an argument that this approach can be generalized to all differences, but one counterexample is sufficient to show that the principle "Distinctions are based on differences" doesn't necessarily lead to vicious regress.

That's interesting, will think about it. 

musiclover wrote:

Feser writes that if something's essence and existence were identical, then that thing would be existence itself. Why think that? This seems to leave out the possibility that that thing would be identical with its particular act of existence, as opposed to existence itself..

This is true. Were it the case that Platonic Properties, Numbers, States-of-Affairs and other such abstract entities existed then they would be as you e.g. their essence would be inseperable from their existence but not identical to it.

musiclover wrote:

He also writes that, if there more than one thing that's existence itself, then something would have to differentiate them. But why not take their difference to be brute? After all, to avoid regress, we need to take something as brutely distinct.

Strictly speaking we take somethings as primitive and thus self-explanatory rather than brute. Even if we go with Bruteness the problem here mentioned still arises in that it would be impossible in principle to give any set of identity conditions.
 

musiclover wrote:

Scott - Yes, but do you agree that a being whose essence is identical with *its* existence is not existence itself?

Not if you also claim and argue, as Thomists do, that the Being is also the ground of all other being.