…then to Aquinas and whether or not he considered the soul to be immortal, and the concurrent issue concerning whether or not the soul is separate from the body. I found an entry to the Routledge Encyclopedia of Philosophy, by Richard Swinburne on this issue, http://www.newdualism.org/papers/R.Swinburne/Swinburne-Nature%20of%20Soul.pdf When we read the first few paragraphs, we get good synopsis of the problem. The issue rests on the transition from an Aristotelian version of the soul (psyche, Ψυχῆς) as intrinsically connected to the body. That is, Aristotle believed that the soul is the animating part of a person’s body–when the body died the soul dies with it. Given that Aquinas is Aristotelian, he mentions this very notion in the Summa Theologica, giving all of us the impression that he agrees with Aristotle, that the death of the body entails the death of the soul.
Yet it is not the case that Aquinas thought that the soul simply died with the body, or that the soul was not immortal. The easy way to think of this would be to recall that Aquinas is advocating a notion of resurrection. If a body is to resurrect with the body it once inhabited, the soul must live without the body until judgment day when the soul becomes embodied. Then according to Aquinas, the person resurrects from the dead to live on into eternity in heaven or hell. The questionable part comes with the notion of what the soul consists of while it is separate from its material matrix, its body. Does the soul lose its identity when it is not animating the body? As Swinburne indicates, Aquinas thinks that the soul is somehow “fitted” to its original body, perhaps like a key to a lock. The other point I am not sure of is what happens to the material body after it is judged.