I found a passage in De Ente et Essentia that is relevant to my claim that Thomas is not a hylomorphist with respect to the human soul but a substance-dualist. Here is the passage in the Armand Maurer translation. The numbers in brackets are my interpolation. My commentary follows.
[1] This is why among these substances [created intellectual substances] we do not find a multitude of individuals in the same species . . . except in the case of the human soul because of the body to which it is united. [2] And even though the individuation of the soul depends on the body as for the occasion of its beginning, because it acquires its individuated being only in the body of which it is the actuality, it is not necessary that the individuation cease when the body is removed. [3] Because the soul has a separate being, once the soul has acquired its individuated being by having been made the form of a particular body, that being always remains individuated. [4] That is why Avicenna says that the individuation and multiplication of souls depends on the body as regards its beginning but not as regards its end. (On Being and Essence, 2nd rev. ed, 1968, The Pontifical Institute of Medieval Studies, pp. 62-63.)
Commentary
Ad [1]. Created intellectual substances are either angels or human souls. Angels, of which there are many, are wholly immaterial. They are nonetheless composite beings in that they do not exist in virtue of their essence (quiddity) but receive their existence from God. Since there is no matter-form (hylomorphic) composition in them, what makes them many cannot be matter. And so each is a species unto itself. Their numerical difference is a difference in species.
Human beings, by contrast, all belong to the same species where the genus is animal, the species is human, and the specific difference is rationality. “Man is a rational animal.” The numerical difference of human beings among themselves is therefore not a difference grounded in a difference of species but a difference grounded in a difference in designated matter (materia signata).
Ad [2]. We are then told that a human soul first begins to exist when it acquires a body. Human souls do not pre-exist their embodiment. This is because the human soul is individuated — made to be an individual soul — by its acquisition of a body. Before Socrates acquired a body, there was no individual Socrates. Socrates cannot exist in reality except as an individual human being and he cannot exist as an individual human being without a material body. It is embodiment that brings about his individuation. So far, so good. No problem.
Now comes the crucial inference: because the human soul acquires its individuated being (existence) in the material body of which the soul is the actuality, it is not necessary that the individuation cease when the body is removed. Why not?
Ad [3]. The reason is because the soul’s individuation brings it about that the soul is a separate being. Unfortunately, Aquinas appears to be equivocating on ‘separate.’ No doubt the individuation of the soul of Socrates bring it about that his soul is separate from Plato’s soul in the sense of numerically different from Plato’s soul. But that is not to say that the soul of either is separate in the sense of existing without a body either before or after death.
I now explain the two senses of ‘separate.’
The cat is on the mat. The cat is separate from the mat, and the mat from the cat. That is equivalent to saying that cat and mat are numerically different. But neither is separate from designated matter. So ‘separate’ has these two different senses. Separation in the first sense is a symmetrical dyadic relation. It is existence-entailing on both ends: if x is separate from y, then x, y both exist. Separation in the second sense is not a relation at all. A separate substance such as an angel is not separated from anything at all. There is no parcel of designated matter that the angel Gabriel has to be separate from to be a separate substance.
So it looks as if Thomas is equivocating on ‘separate.’ But let’s be charitable. Even if Thomas is not equivocating on ‘separate,’ his argument remains puzzling. Angels are separate substances: although not self-subsistent like God, they subsist without matter. They are individual in themselves, as forms. They need no individuation ab extra. They are already, logically speaking, individuals. Socrates does need individuation ab extra, and it comes from matter. Before he began to exist, he was nothing in reality: he was not a subsistent individual form that acquired a body. He became an individual only when a certain soul-body/ form-matter composite came to be. How then can the soul or form of that composite continue to exist when the composite is no more? This is impossible on Aristotelian hylomorphism, according to which the ‘principles’ of a hylomorphic compound substance are not themselves substances but non-independent ontological ‘parts’ or constituents of the substance of which they are the constituents.
Is Aquinas telling us that when Socrates died he became an angel? I reckon not. (That would be quite the metabasis eis allo genos!) Not even the doctor angelicus became an angel at death. He is however telling us that when the philosopher died he became a separate intellectual substance, and thus like an angel in that respect.. Bear in mind that for Thomas, an incomplete substance is a substance. An incomplete substance is logically capable of independent existence: it is not an accident of a substance nor a ‘principle’ of a substance.
So, while Socrates post-mortem is no angel, sensu stricto, he is a separate intellectual substance, a substance that exists in reality on its own without matter. How exactly, given that for humans, as opposed to angels, (designated) matter is the principium individuationis?
The Aquinate line seems to be that the individuation that human souls acquire from matter before death remains with those souls after death. But what is the argument for this surprising thesis? The only argument I discern in the above text is this:
a) Designated matter individuates human souls;
b) Such individuation by designated matter makes of the soul a separate substance;
c) A separate substance does not depend on matter for its subsistence; ergo,
d) A human soul once individuated is forever after a separate substance.
But what reason do we have to accept (b)? No reason at all on a strictly hylomorphic approach. In fact, such an approach rules out (b). The form or soul of a living substance such as Socrates is merely a ‘principle’ of this compound sublunary substance — as I have stated many times already. These principles are not themselves substances. So they cannot exist on their own. Hence they cannot exist without matter. On strict hylomorphism, the soul of Socrates cannot continue to exist upon the dissolution of his body.
Everything falls into place, however, once you see that Aquinas is not a hylomorphic monist, but a substance-dualist. He simply presupposes the truth of (b). This presupposition is logical ‘fallout’ from Christianity as he understands it
Bill,
This post, along with the two that preceded it, are outstanding, first because of their rigorous critical analysis of Aquinas’ position on hylomorphism and the post mortem soul and second because of their clarity and eloquence. Although I am no philosopher, I have been reading and thinking about this problem for many years now, and, for whatever my opinion is worth, I do not see how one might effectively counter the argument that you present. I hope that your critics do not cloudy the discussion by insisting that you either (1) have not understood something basic about hylomorphism, which is clearly false, or (2) by simply assuming the survival of the human soul because when embodied it carries out immaterial operations.
Vito