Rather do we claim that the Word in an unspeakable, inconceivable manner united to himself hypostatically flesh enlivened by a rational soul.... Rather did two different natures come together to form a unity, and from both arose one Christ, one Son. It was not as though the distinctness of the natures was destroyed by the union, but divinity and humanity together made perfect for us one Lord and one Christ, together marvellously and mysteriously combining to form a unity.
So what do we have here? We have, first, a divine person (the Word of God) 'hypostatically' united to 'flesh enlivened by a rational soul'. 'Hypostatically', for our limited purposes here, can be treated as a synonym for 'personally'. To say that the Son of God was hypostatically united to flesh enlivened by a rational soul is to say that He was personally united to it; that is, this very person, the Son of God assumed or took up fleshly rational life. Note what does not follow from this.
1. It does not follow from this that the Son of God ceased to be a person of the Trinity. Quite the contrary - the whole point is that this very person of the Trinity was enfleshed.
2. It does not follow from this that the Son of God was somehow turned into flesh; all that follows is that He was united to it.
3. It does not follow that the Son of God took up or assumed a human person; all that follows is that He took up human flesh, life, and reason. (More on this below.)
4. It does not follow that the Son of God was somehow turned into a human person (merely); all that does follow was that the Son of God became man, which allows for an interpretation under which the Son of God does not cease to be God. As we noted in (1), this is the whole point.
5. It does not follow that divine and human natures ceased to be distinct in Christ; all that follows is that they were united.
These sorts of considerations led to the clarification put forward by Chalcedon in the Definition of the Faith, which said that there was
one and the same Christ, Son, Lord, only-begotten, acknowledged in two natures which undergo no confusion, no change, no division, no separation; at no point was the difference between the natures taken away through the union, but rather the property of both natures is preserved and comes together into a single person and a single subsistent being; he is not parted or divided into two persons, but is one and the same only-begotten Son, God, Word, Lord Jesus Christ
There are, then, two natures under consideration in the Incarnation: a human nature and a divine nature. In the hypostatic union, i.e., the personal union in which the Word became flesh, these natures are united without ceasing to be distinct, and are distinct without ceasing to be united. They are distinct as natures: being divine is, and always will be, something different from being human. But they are united in the one person who became incarnate, namely, the Word. Two distinct natures of one single person. Since the sort of things one can do depend on one's nature, throughout His earthly life, Christ was engaged in two types of action, human actions and divine ones. As Athanasius says in the same text noted above,
You must understand, therefore, that when writers on this sacred theme speak of Him as eating and drinking and being born, they mean that the body, as a body, was born and sustained with the food proper to its nature; while God the Word, Who was united with it, was at the same time ordering the universe and revealing Himself through His bodily acts as not man only but God.
William Vallicella in an interesting article has raised this issue about the consistency of the Incarnation. The doctrine leads, he says, to the following incompatible triad:
1. Necessarily, if two things are identical, they share all their (non-intentional)properties.
2. God the Son and Jesus do not share all their (non-intentional) properties.
3. God the Son and Jesus are identical.
An example of an 'intentional property' would be believed to be the Son of God. Naturally, it would be possible for someone to believe that God the Son is the Son of God without believing that Jesus is the Son of God; this really doesn't, and shouldn't, have any affect on our discussion here, so the "non-intentional" here sets those properties aside.
Vallicella considers this triad to encapsulate what he calls the "Orthodox Chalcedonian incarnationalism" or OCI. Vallicella is quite right that the triad he presents is an incompatible one. He is quite wrong to think that this triad is OCI. The problem is with the identity thesis (3): it is only superficially similar to the genuine Orthodox thesis, which is that the Word of God and Jesus are one person. To see this, consider the following example (apologies for the lowliness of it):
Brandon without clothes is the same person as Brandon with clothes; but Brandon without clothes is not logically identical to Brandon with clothes, because in putting on clothes I add non-intentional properties to my person. Having clothes and not having clothes are not the same thing.
Likewise (mutatis mutandis, of course), the Word of God is the same person as the Incarnate Word of God; but the two are not logically identical, because the Word of God can be unincarnate as well as incarnate. It is not necessary for the pre-incarnate Word to have all the same properties as the incarnate Word; indeed, that would defeat the whole point of the Incarnation, which is the doctrine that the unincarnate Word took on incarnate properties. The unincarnate Word is still the same person as the incarnate Word. There are not two persons, one unincarnate, the other incarnate; but there is one person, who has in the one case additional properties. This, you will note, is what the Chalcedonian definition says. (3), which is the culprit in the incompatible triad, is a false characterization of Chalcedon and orthodoxy.
A major temptation of those with a sophisticated philosophical background, in this area as in the area of Trinitarian theology, is to treat the matter as a question of logical identity. It is not, and treating it as though it were inevitably will tie you in tangled knots. It is not surprising that such people begin to think of the doctrine of the Incarnation as involving contradictions. It is fairly easy to show that there is only one way in which the basic doctrine of the Incarnation could be shown to involve contradictions. Contradictions can only arise if X is A and Y is ~A in the same respect. It would be a contradiction, for instance, if Christ were God and not-God in exactly the same way. But this, of course, is not the doctrine of the Incarnation. Christ is God because He is the Word; He is also human, and only in that sense not-God. This is the whole point of Chalcedon, which has resoundingly and effectively closed off any attempt to locate an easy contradiction in the doctrine: Christ has both human and divine properties; for there to be a contradiction in this, Christ would have to have conflicting properties (e.g., omnipresence and containment in a limited space) in the same way. Christ (in his divine nature) has some properties (divine ones) and Christ (in his human nature) has some properties (human ones); what is true of Christ as God may not be true of Him as man, and vice versa. This sort of statement, in which we say, "X as Y is Z" is called a 'reduplicative statement'; and one of the things reduplicative statements do is block straightforward contradictions.
They do not block all contradictions. In this case the reduplicative or two-natures response leaves open one way in which a contradiction could arise: namely, if it could be shown that there is a contradiction in one person being the subject of both divine and human natures. While I think there is a solution to this implicit in what has already been said, it is clearly the case that showing this route to contradiction is blocked is more difficult; Chalcedon doesn't explicitly show it. To see it we have to turn from the Council of Chalcedon (451) to the Third Council of Constantinople (680-681).
In my experience, the single biggest stumblingblock people face to accepting the integrity of the doctrine of the Incarnation is this. We tend to think of ourselves as our minds; and thus people construct the following sort of dilemma: if God has taken up 'flesh enlivened by a rational soul' He can only do so by 1) taking up a human person; or 2) taking up less than what is required for a human person. The reasoning is that if the Word assumes a rational soul, he assumes a mind and therefore a person; but if He does not assume a person, He does not assume a rational soul and therefore does not become human. If this dilemma is acceptable, the sort of contradiction noted above would arise.
However, if by 'divine mind' we mean 'divine capability for thinking' and by 'human mind' we mean 'human capability for thinking', then there is no clear sense in which this would be the case. It is not clear what else we could mean. And a single person can have two different capabilities, e.g., a physical capability for walking and a mental capability for reasoning. And this is, in essence, the point of the Constantinople III. They put it in terms of will rather than intellect; the reason I put it in terms of intellect is that this is where the problem arises nowadays. But the two cases are closely parallel. As the council said of wills:
And we proclaim equally two natural volitions or wills in him and two natural principles of action which undergo no division, no change, no partition, no confusion, in accordance with the teaching of the holy fathers. And the two natural wills not in opposition, as the impious heretics said, far from it, but his human will following, and not resisting or struggling, rather in fact subject to his divine and all powerful will.
The only way to argue for a contradiction in the doctrine of the Incarnation, then, is to argue that it is logically impossible for one person to have two different capabilities (whether intellectual or volitional), one subordinate to the other. I don't have an argument that such an argument is impossible; but we can, I think, reasonably ask, on what basis would we make such an argument? Certainly on no basis proposed so far; and it seems doubtful, even from the point of view of mere reason, that we could absolutely rule out the possibility of one person having "two natural wills not in opposition".
I put a "Part I" in my title for the same reason I did so with my Trinitarian post; all this is very rough and incomplete and will, no doubt, need a sequel at some point.
UPDATE (24 Aug 2004): Vallicella has put up a helpful response to my argument; it seems clear that I misunderstood his argument in some way. I'm leaving the above post untouched both because it was a first draft anyway, and because I still think its positive points are all quite right and, while the position attributed to Vallicella might not be his, these sorts of criticisms do come up. For a link to Vallicella's response and my further puzzlings about his argument, see this post.