Book Two — Creation, Chapter 80 — Summa Contra Gentiles
ARGUMENTS TO PROVE THAT THE CORRUPTION OF THE BODY ENTAILS THAT OF THE SOUL [AND THEIR SOLUTION]
[1] There are certain arguments which would seem to prove the impossibility of human souls remaining after the body.
[2] For, if human souls are multiplied in accordance with the multiplication of bodies, as was shown above, then the souls cannot remain in their multiple being when the bodies are destroyed. One of two alternatives, therefore, follows ineluctably: either the human soul perishes utterly, or only one soul remains. And, seemingly, this state of affairs would accord with the theory of those who maintain that what is one in all men is alone incorruptible, whether this be the agent intellect only, as Alexander declares, or, in the Averroistic doctrine, the possible along with the agent intellect.
[3] Moreover, the formal principle [ ratio ] is the cause of specific diversity. But, if many souls remain after the corruption of bodies, they must be mutually diverse; for just as there is identity where there is unity of substance, so those things we diverse which are substantially many. Now, in souls that survive the death of the bodies which they inform, the only possible diversity is of a formal character, since such souls are not composed of matter and form—a point proved above with respect to every intellectual substance. It therefore follows that those souls are specifically diverse. Nevertheless, souls are not changed to another species as a result of the body’s corruption, because whatever is changed from species to species is corrupted. Consequently, even before souls were separated from their bodies, they were specifically diverse. Now, composite things owe their specific nature to their form. It follows that individual men will be specifically diverse—an awkward consequence. It is, therefore, seemingly impossible that a multiplicity of. human souls should survive their bodies.
[4] Then, too, for those who espouse the doctrine of the eternity of the world it would seem utterly impossible to maintain that a multiplicity of human souls remain after the death of the body. For, if the world exists from eternity, then movement did, too, so that generation likewise is eternal. But in that case an infinite number of men have died before us. If, then, the souls of the dead remain in their multiple being after death, it must be said that there actually exist now an infinite number of souls of men already dead. This, however, is impossible, because the actually infinite cannot exist in nature. Hence it follows, on the hypothesis of the world’s eternity, that souls do not remain many after death.
[5] Also, “That which comes to a thing and departs from it, without the latter being corrupted, accrues to it accidentally”; for this is the definition of an accident. Thus, if the soul is not corrupted as the result of its severance from the body, it would follow that the soul is united to the body accidentally, and, further, that man is an accidental being, composed of body and soul. In that case, too, we should be faced with the consequence that there is no human species, for one species does not result from things joined together by accident; white man, for example, is not a species.
[6] A completely inoperative substance, moreover, cannot possibly exist. All psychic operation, however, is corporeally determined, as we see by induction. For the soul’s nutritive powers function through the bodily qualities, and by a bodily instrument acting upon the body, which is perfected by the soul, which is nourished and increased, and from which the seed is separated for generative purposes. Secondly, all the operations of the powers belonging to the sensitive soul are executed through bodily organs, some of them entailing a certain bodily transmutation, as in those which are called passions of the soul, for instance, love, joy, and the like. And again, while understanding is not an operation carried out through any bodily organ, nevertheless its objects are the phantasms, which stand in relation to it as colors to the power of sight; so that, just as sight cannot function in the absence of colors, so the intellective soul is incapable of understanding without phantasms. Moreover, to enable it to understand, the soul needs the powers which prepare the phantasms so as to render them actually intelligible, namely, the cogitative power and the memory-powers which, being acts of certain bodily organs and functioning through them, surely cannot remain after the body perishes. And that is why Aristotle says that the soul never understands without a phantasm, and that it understands nothing without the passive intellect, which he terms the cogitative power, and which is destructible. This explains why he says in De anima I [4] that man’s understanding is corrupted through the decay of some inward part, namely, the phantasm, or the passive intellect. Aristotle also remarks in De anima III [5] that after death we do not remember what we know in life. Evidently, then, no operation of the soul can remain after death. Therefore, neither does its substance continue to be, since no substance can exist without operation.
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