"I believe in . . . the resurrection of the body and life everlasting." Thus ends the Apostles' Creed. Joseph Cardinal Ratzinger (Pope Benedict XVI) addresses the meaning of this article of faith on pp. 347-359 of his Introduction to Christianity (Ignatius Press, 2004). The book first appeared in German in 1968 long before Ratzinger became pope. Herewith, some interpretive notes and commentary.
1) Despite the undeniable Platonic elements in Christianity, to which Ratzinger is sensitive, the Biblical promise of immortality pertains to the whole man, not to a separated soul. Some, Lutherans in particular, recoiling from Platonic soul-body dualism, have gone so far as to maintain that the Greek doctrine of the immortality of the soul is positively un-Christian. (347) This is going too far. It is clear, though, that on Christianity a man is not in his innermost essence a pure spirit like an angel; he is, by nature, a corporeal, embodied being whose ultimate good is to live forever in an embodied, not an angelic, state.* 'By nature' implies that we are not accidentally embodied, as on Platonism, but essentially embodied.
2) On the other hand, the idea of immortal (living) bodies, immortal animals, seems utterly absurd given what we know about the natural world, as Ratzinger admits (348). Schopenhauer mocks this notion as immortality mit Haut und Haar, with skin and hair. By contrast, the notion of human immortality as the immortality of a simple (metaphysically incomposite) soul substance is not absurd but defensible, even if not Christian.
So we face a problem. Platonic dualism cannot do justice to our unitary corporeal nature. It involves an ontological denigration of the body and of materiality in general. The material world, however, created by God, is good, and not to be flown from in Platonic-Plotinian-gnostic fashion. The body is not the prison house of the soul, but something rather more positive: its necessary expression or realization. But how on earth could the living bodies of humans live forever?
3) One solution that suggests itself -- call it the additive solution -- is to add the Biblical notion of bodily resurrection to the Platonic notion of soulic immortality. When you die, soul and body separate: the soul continues to exist while the body returns to dust. ("Remember man, thou art dust, and unto dust thou shalt return . . .") At the end of the world, the dead are raised and a soul is reunited with its body, the same one it had on Earth, although presumably spiritualized and transformed or transfigured. Although Ratzinger does not cite Aquinas in the stretch of text I am commenting on, the Angelic Doctor's view is additive.
On this view, (i) resurrection is resurrection of the (human) body, not of the whole man, and (ii) this resurrected body will be numerically identical to the body that lived and died on Earth. In other words, the pre-mortem and post-mortem bodies of a resurrected person are one and the same. After the resurrection you will have the very same body that you have now. This is compatible with the resurrected body being property-wise different from the earthly body. I take this same-body view to be the traditional view. We find it, for example, in Aquinas:
For we cannot call it resurrection unless the soul return to the same body, since resurrection is a second rising, and the same thing rises that falls; therefore resurrection regards the body which after death falls, rather than the soul which after death lives. And consequently if it is not the same body which the soul resumes, it will not be a resurrection, but rather the assuming of a new body. (1952, 952, quoted from here)
For the sake of concretion, let's assume the Aristotelian hylomorphic dualism of Aquinas according to which a human being is a composite of soul and body where the soul is the form of the body. For Aquinas, the soul continues to exist after the body ceases to exist, and resurrection is the uniting of that soul with its body, not some body or other, but its body, the same one it had on Earth, although perfected, subtilized, spiritualized, and rendered free of defects.
4) The Thomistic synthesis of the Greek and the Biblical is an uneasy one, fraught with difficulties. I'll mention just one. On the Platonic view, salvation is salvation of the soul from the body; it is not the salvation of the whole, undivided, man. The soul is a naturally immortal spiritual substance** that comes into its own only when freed from the evil predicament of embodiment. Death, as separation of soul from body, is release and therefore something good. The Biblical conception is very different: death is not good, but bad: the fitting punishment for Adam's sin. Death is not a welcome release from the material world, but the calamity of all calamities. We were intended by God to live forever in Paradise in an embodied, material form. But Adam (man) fell, and is now subject to sickness, old age, and death in a material world that is itself fallen and in which demonic agents are at play in various ways.
Now suppose you are a philosopher and a Christian who wants to find a way to accommodate man's essential corporeality. Following Aristotle, you bring Plato's Forms down to Earth where they cease to be substances in their own right and become factors in the ontological analysis of such sublunary substances (prote ousiai) as statues, horses -- and humans. Socrates, then, is not a naturally immortal soul accidentally attached to a perishable body, but a hylomorphic compound of form and (proximate) matter in which anima forma corporis, the soul is the form of the body.
The soul, which was a substance for Plato becomes in Aristotle a non-substantial 'principle' invoked in the analysis of genuine substances. The I that thinks when Socrates thinks is then presumably not his soul but the whole man, the entire hylomorphic compound. That which thinks when Socrates thinks is Socrates, not the form of his body. For how could an enmattered form think? How could it be the subject of thinking (of cogitationes in the broad Cartesian sense)? An enmattered form is a respect in which a sublunary substance is intelligible, but it is not intelligent, being merely one factor in the ontological analysis of a whole man who is the one doing the thinking. A subject of thinking must be a substance, and on the Aristotelian analysis, the soul is not a substance but a form.
Might it be, contrary to what I have just maintained, that the soul is an enmattered form that is both intelligible and intelligent? If so, then the soul-form is what I refer to when I thoughtfully deploy the first-person singular pronoun, and not the whole man, body-cum-soul. This seems to lead us back to the view according to which I am identical to my soul, and away from the Aristotelico-Thomist view according to which I am not identical to my soul, but identical to a composite of soul and body.
To state the problem succinctly, Thomas is an Aristotelian on Earth, but a Platonist in heaven, and he has to be both to satisfy simultaneously the exigencies of both Christianity and Aristotle. But the exigencies are in tension one with the other, a tension tantamount to contradiction. Thomas qua Christian needs a substantial soul capable of surviving bodily death, a soul that then 'waits' for its completion in the resurrection of the body. Qua Aristotelian, however, the soul must be a form and not a substance. The upshot is a contradictory construct: a form that is and is not a substance. A soul-form which is not a substance but a principle when embodied, becomes a substance on its own after death.
5) Ratzinger rejects the additive approach to resurrection. A restored body is not added to a post-mortem soul. For "the biblical train of thought . . . presupposes the undivided unity of man." (349) Scripture speaks of "the awakening of the dead, not of bodies!" (349) The "real heart of the faith in resurrection does not consist at all in the restoration of bodies . . . ." (349) Man is not composed of body and soul with the soul the carrier of his immortality. If you start with that conception, then resurrection becomes the restoration of bodies, which are then added onto the souls which have been waiting for their bodily completion. This scheme is precisely what Ratzinger is opposing. So how does he propose that we understand resurrection?
6) He speaks of a "dialogic immortality" that is an "awakening."(350) Man cannot "totally perish because he is known and loved by God." (350) As against Platonism, there is nothing in man that is indestructible. Man is saved from annihilation by being drawn into dialogue with the Creator. In this way the whole man, not just his soul, is awakened and brought to life.
From here on out the discussion tapers off into vagueness. Resurrection is not a restoration of one's earthly body. The person "goes on existing because it lives in God's memory." (353) To go on existing as a merely intentional object of someone's memory, even of God's, seems insufficient. I remember my mother, but does she live on in my memory? Such an afterlife would be a paltry thing indeed, and not just because my memories of her are both incomplete and in some respect erroneous. The main problem is that an object of memory cannot, by being remembered, be transformed from a non-living subject into a living one. My memory cannot be constitutive of your subjectivity. But perhaps with God it is different . . . .
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*While man is not a pure spirit, the Christian worldview admits the existence of finite pure spirits, namely angels and demons (fallen angels). Christianity is therefore not a materialist worldview: it does not hold that finite intelligence cannot occur except as physically realized or materially embodied. And of course God himself, the infinite, archetypal spirit, is a pure spirit, fully real, and fully concrete, despite being wholly immaterial. Christianity is not materialism, but it does, in the teeth of Platonism, valorize the material world.
**An individual substance is definable as anything metaphysically capable of independent existence.