Classical Theism, Philosophy, and Religion Forum / Why do Thomists introduce prime matter with substantial change?

**Posted by RomanJoe** 4/14/2018 2:11 pm

It seems to me that many Thomists like to introduce the principle of prime matter through an analysis of substantial change. But doesn't prime matter account for change in general? I mean the fact that a substance can move from location A to location B presupposes that there's some undetermined yet determinable substratum that needs to be actualized. Existing in location B can't come about unless there's a correlative principle to act that can help bring about existing at location B.

Last edited by RomanJoe (4/14/2018 2:12 pm)

**Posted by John West** 4/19/2018 6:18 pm

I'm not completely sure what it is you're trying to find out, but there is a nice article on prime matter and the problems with it here.

**Posted by RomanJoe** 4/19/2018 10:34 pm

John West wrote:
I'm not completely sure what it is you're trying to find out, but there is a nice article on prime matter and the problems with it here.

Thanks. I actually recently read that article and found it really informative. I guess what I'm saying is that to say a substance has a potential for an actual existence (an apple has a potential to actually exist as a sliced apple) is to presuppose that there is something about that substance that is not yet determined but can nonetheless be determined. Scholastics usually say that in accidental change (an apple is sliced, water is heated, a man changes location) the substance is the subject of change, while in substantial change (a lion is burned to ashes) an underlying purely potential substratum is the potential for change. But given that the scholastic supposes that all substances are composite of prime matter, then even an accidental change requires a different configuration of prime matter. For example, a man is a composite of form and prime matter in location A and in location B. But in location B his composition has changed--that is, different potencies in his prime matter are actualized (given that prime matter is the substratum of potency). So, without prime matter, the scholastic would argue, there can be no change.

I was just wondering why there is such emphasis on substantial change as an evidential factor for prime matter and not change in general. For surely prime matter is fundamental to even accidental change.

Last edited by RomanJoe (4/19/2018 10:37 pm)

**Posted by John West** 4/19/2018 10:44 pm

It seems to me you're running prime matter and secondary matter together. Prime matter is the substratum of substantial change; secondary matter is the substratum of accidental change. It's the latter that would be different, if either is different, in cases of accidental change.

**Posted by RomanJoe** 4/19/2018 10:50 pm

John West wrote:
It seems to me you're running prime matter and secondary matter together. Prime matter is the substratum of substantial change; secondary matter is the substratum of accidental change. It's the latter that would be different, if either is different, in cases of accidental change.

But even in accidental change there would be an alteration in prime matter, no? Since prime matter is also regarded as a principle of limitation, with humanity being limited to this human, that human, and that human, then when a man changes location he is being limited to locale x instead of locale y and z.

**Posted by John West** 4/19/2018 11:01 pm

I recall something about prime matter being a principle of limitation, but it's not for every limitation. It's not, for instance, the principle doing the limiting in the case of angels if Thomas is right about them having no matter. They have potency (e.g. they can cease to exist), but not matter.

By the way:

Since prime matter is also regarded as a principle of limitation, with humanity being limited to this human, that human, and that human

It's not prime matter that individuates the bearer-specific instance of humanity that (say) you instantiate. It's materia signata quantitate or “matter signed by dimensive quantity”. (I have no idea what the relation between humanity-in-itself, which according to Thomas is neither universal nor particular, and the instance is.)

**Posted by John West** 4/19/2018 11:09 pm

I'm going to be away for a few weeks. Well, lots of Thomists to pick things up in my place.

**Posted by John West** 4/23/2018 5:11 pm

I expected the Thomist army to descend upon this thread with screeches and howls:

I was just wondering why there is such emphasis on substantial change as an evidential factor for prime matter and not change in general. For surely prime matter is fundamental to even accidental change.

I'm assuming your argument is something like (i) there is accidental change; (ii) secondary matter is needed for accidental change; hence (iii), there is secondary matter; (iv) secondary matter is just prime matter's having a substantial form; hence (v), there is prime matter.

But how do you know secondary matter is needed for accidental change? There are other attempts to account for the datum of (to use a more theory neutral term) alterational change, and not all of them are easily refuted (e.g. contemporary powers theorists').

It might also be worth your time to look into whether Aquinas thinks angels can undergo accidental change. I have a faint memory of Ed suggesting that they can't (or my thinking he had, anyway) and getting swarmed by theologians insisting that there are strong scriptural reasons for believing that they can.

Anyway, good luck.

**Posted by ficino** 4/23/2018 8:12 pm

Angels are not the subjects of spatial motion properly speaking, but they are subjects of temporal motion, for they think discursively and perform acts of will. Angels can also conduct operations via the element, air, in a given place, and can act via a body not their own, since they can be perceived by more than one human at once. Angels of course have no matter. They are composite of form and an act of existence, not composite of form and matter plus an act of existence as embodied creatures are.