RomanJoe,
In your first comment here you distinguish between two pure acts, as it were, the first pure act being relevant to causal efficacy in the per se causal chain, the second the pure act of existence of the thing having said causal efficacy. For the difficulty to make sense, these things would have to be really distinct, not simply logically, as in the latter case you would simply have one pure act, and in the order where the act is pure there's simply no 'space' for any potency admixed (to wit, as the act wouldn't merit the characterisation as 'pure').
Now, the thing in question has to be a substance. It cannot be a merely accidental unity, as in that case both 'parts' would have substantial identity, and hence be two different things, one, however, dependent on the other (since, as you grant, existence precedes causal efficacy). That dependence, moreover, would be causal, as the first thing's potential to exist would have to be actualised first, so we have the same regress again and only the latter thing would merit the name of prime mover.
That leaves us with both pure acts being said to be acts of one and the same thing. That's where parts come in. Now, whatever a part is, it is really distinct from the whole.
If we are talking of physical (not "material' or 'bodily'; the term connotes relevance to the things activity) parts of a substance, in order to 'fit' at all, they have to be accidents. Yet, accidents are -dependent- on the substance (their existence is derivative of the substance, and hence we have an actualised potency). Further, accidents are determinations of the substance, and hence the substance is also potential in respect of the accident (it really can be so determined). So the 'efficacious' pure act (the power, clealy) cannot be had (as an accident, and these are only had by substances). And if it cannot be had, but has to obtain (as it does, in order to explain the causal series), it leaves us with it simply being.
Last edited by GeorgiusThomas (11/26/2017 4:17 pm)