[Serious] Book reports

[Belacqua]

Feser finally addresses quantum mechanics in the section on efficient causality but does so in a rather unsatisfying way. Feser basically says: so what, nothing in Aquinas's metaphysics necessitates that determinism be true anyway, no biggie. But if things do/can occur in an indeterministic manner, then doesn't this suggest some lack of directionality, and wouldn't this therefore be a problem for Aristotelian causality in general? 

Here's the part where I think he deals with that -- or tries to. This is page 54 in my paper copy of the book:

It is sometimes suggested that quantum mechanics undermines the principle of causality insofar as it implies that the world is not deterministic. But the Aristotelian does not regard the world as deterministic in any case (determinism being a view associated with the mechanical conception of nature Aristotelians reject), and thus does not hold that every cause must be a deterministic cause. As the analytical Thomist John Haldane has noted, if we can appeal to objective, non-deterministic natural propensities in quantum systems to account for the phenomena they exhibit, this will suffice to provide us with the sort of explanation the Aristotelian claims every contingent thing in the world must have.

I think this deals with the issue pretty well, but doesn't unpack the terms in the way that some of his other explanations do. It wouldn't make sense to me if I hadn't read Burtt's book on the metaphysics of science, and some other things on the changes in metaphysics around the time of Galileo and Newton. 

I am of course no expert, but I'll take a stab at it this way: 

The "mechanical conception" of nature which he mentions is sort of like clockwork. Every gear that turns has to be pushed by another gear, and every little cuckoo that sings on the hour has to be triggered by a spring that is released by a latch that is pushed by a gear. These are the type of things he means (I think) when he talks about "deterministic" causes. The gear determines what the latch will do, the latch determines what the spring will do, etc. 

This is probably our normal conversational way of using the word "cause." And as we've seen, people are reluctant to think about uses of words which are different from our modern popular usage. But Aquinas used "cause" in different ways, as you've read.

The non-mechanical, non-deterministic type of cause that we need instead is alluded to when he says "objective, non-deterministic natural propensities in quantum systems to account for the phenomena they exhibit." In such a case, a cause isn't object A pushing object B, but just the natural inherent tendency of A to do a certain thing. 

People who assume all talk of causation is efficient mechanical deterministic causation triumphantly point to radioactive decay of particles as proof that things occur without causation. The decay of the particle appears to happen without anything pushing or triggering it. But this is no problem for a Thomist, who says that a cause may also be the natural propensity of a radioactive particle just to decay. 

The cause of the decay is the natural propensity of the particle; a part of the particle's essence is that it will at some point decay. It need not be mechanically triggered. 

Feser, however, lost me once again with the angel stuff. I don't think he did well enough at distinguishing between angels and Platonic Forms. Pure forms existing concretely yet independently of matter still doesn't feel like it makes sense.

I guess I enjoy the angel talk because it shows cases of how different things could show the various qualities that he talks about. As he says, a thing need not actually exist for us to talk about its essence. So I don't think we have to believe in angels to take them as thought experiments. 

That said, angels are pretty different from Platonic Forms. 

I think Platonic Forms are supposed to be

~ universal
~ uncreated (in the mind of God all along)
~ without location
~ without extension (this is the same for angels -- they have location but not extension)

Angels, on the other hand, would be:

~ individual (There's only one Raphael, one Michael, one Uriel, etc. If Aquinas believed in Platonic Forms, there would be a Platonic Angel Form that exists "above" each particular angel's existence.)
~ created 
~ having location (an angel can be said to be in a certain place and not in another)

Very roughly, maybe an analogy would be that numbers are a little like Forms while particular thoughts are a little bit like angels. The number 2 is universal, uncreated, doesn't exist in any particular place, and has no size. A particular unique thought which is currently in your mind, however, is particular to you, was created by you, and is located in your mind. Neither is made of matter, but the way they exist is different.

And thank you again for working on this with such diligence! It's a real pleasure for me to look at it again with such good motivation!!!