The Same, Yet Different

An essay I wrote last semester for a seminar class, in response to Thomas Morris' "The Logic of God Incarnate":

In this essay I will attempt a solution to the following problem: How could God the Son and Jesus of Nazareth be identical? I will argue that contra the approach using the theory of relative identity, a solution to the numerical identity of God the Son and Jesus of Nazareth can be found within the confines of the principle of the indiscernibility of identicals. I will first examine Morris’ treatment of several solutions to this problem, focusing on a solution from the theory of relative identity. After rejecting this approach, I will go on to argue that a solution to the problem can be found by restricting the domain of the sets of properties between God the Son and Jesus of Nazareth being called identical to those of personhood.

In the first chapter of his book The Logic of God Incarnate, Thomas Morris broadly examines the charge that the orthodox understanding of the doctrine of the Incarnation is logically incoherent. Many of those who claim that the orthodox understanding of this doctrine is logically incoherent do so on the grounds that the doctrine violates what we understand about the nature of identity. Many have thought that to say that the incarnate man Jesus of Nazareth is one and the same individual as the second person of the Trinity contradicts the very laws of logic, and some have even said that such a statement is actually meaningless. To combat this charge, Morris takes a look at several approaches to solving the problem.

After rejecting the idea that we should accept the seeming contradiction at work here as a sign of its supernatural descent, and thus devalue all of human logic, Morris next examines the case of those who would reject only those logical doctrines that would cause trouble for the doctrine of the Incarnation, most specifically the principle of the indiscernibility of identicals. The principle of the indiscernibility of identicals says that if x is identical to y, then x and y have all the same properties. To avoid certain logical contradictions within Christian doctrines, philosophers such as A. P. Martinich have argued for a relative theory of identity, in which the indiscernibility of identicals is denied. In summary of the theory, Morris says this: “Simply put, the relativity thesis is that identity is sortal relative. Every statement of the form ‘a is b’ or ‘a is the same as b’ is said to be incomplete. In every such case, we are told, it needs to be asked, ‘The same what?’” Morris then explains further that, under the theory of relative identity, a and b could be the same F but not the same G. Thus, Martinich (as construed by Morris) believes that, in the case of the doctrine of the Trinity, the Father and the Son could be the same God, but not the same person.

Morris expresses concern with this approach to a solution to contradictions found within the doctrine of the Incarnation, and with good reason – the theory of relative identity is, as Morris points out, highly controversial and tends to lend itself to more contradiction than it solves. Morris himself simply glances over the topic without much more than the brief dismissal in his book, but a much more in-depth treatment of the theory as proposed by Peter Geach is given by John Hawthorne in his essay simply entitled “Identity.” In this article, Hawthorne gives several potent objections to the relative identity theory, the most pointed of which deals with the absurdity caused by the theory when it is put into practice. As an example, Hawthorne deals with Geach’s use of the relative identity predicate ‘is a surman,’ where x is the same surman as y iff x is a man, y is a man, and x and y have the same surname. Under this predication, John and his father Patrick Hawthorne would be the same surman (John Hawthorne calls the surman ‘Bob’). However, Hawthorne argues that if this is the case, a myriad of logical problems and contradictions arise. For instance, if John has brown hair, but Patrick has black hair, then what color is Bob’s hair (if he indeed has hair at all)? To defend relative identity here, we would be forced to accept the two following contradictory propositions as true:

Bob has brown hair.
It is not the case that Bob has brown hair.

What are we to do with this? Suppose further that John changes his surname to ‘O’Leary-Hawthorne’ and then changes it back to ‘Hawthorne.’ Similar problems begin to arise here. Now, there are two surmen, Bob and the ‘O’Leary-Hawthorne’ surman (call him Sven). To which of them is John identical? If both, we are forced to accept the following syllogism as true:

If a = b, and b = c, then a = c.
If Bob = John, and John = Sven, then Bob = Sven.

If we accept this as true, as the relative identity theory would have us do, why make the distinction between Bob (‘Hawthorne’) and Sven (‘O’Leary-Hawthorne’) in the first place? What distinguishes each one from the other? These are just two of the problems that Hawthorne points out in the usage of the theory of relative identity. These problems as well as many others need to be worked out if relative identity is going to be a useful theory in metaphysics.

Still, a problem seems to remain in the logic of the doctrine of the Incarnation. However, because the theory of relative identity appears to be a bad solution to our problem, we must not assume that the reasons for attempting to use it were bad ones. Remember back to Morris’ exposition of Martinich’s solution to the seeming contradiction he found in the doctrine of the Trinity. Martinich believed that, in order to make sense of the doctrine, Christians must reject the principle of the indiscernibility of identicals (hereafter referred to as ‘Leibniz’s Law’), and he thus proposed a solution with the somewhat-faulty theory of relative identity. Though his proposed solution seems to cause more contradiction than it solves, Martinich might not have been so wrong to be wary of Leibniz’s Law. For, just as Martinich pointed out in regards to the doctrine of the Trinity, the Law seems to make trouble for the doctrine of the Incarnation as well. Leibniz’s Law states that two things are identical iff they share all the same properties. What then are we to make of God the Son, who before becoming incarnate was incorporeal, becoming the Incarnate Jesus of Nazareth? The two surely differ in at least one property, that of having a body. Morris, however, overlooks this problem completely. He says,

"The only purpose of denying indiscernibility would be to all that there are some properties Jesus had but God the Son lacked, and vice versa. It is hard to see how in the end such a view could avoid the condemnation of Cyril, bishop of Alexandria…. And of course it was the view of Cyril which become recognized as orthodoxy at Chalcedon."

It seems intuitive that the pre-incarnate Son of God and the incarnate Jesus of Nazareth do not share all the same properties, for it would surely be absurd to say that God the Son had hands, feet, nose, or eyes before he was incarnate. Even the Council of Chalcedon would not deny this fact. It must either be shown that they actually do share all the same properties (which seems doubtful considering the act of Incarnation), or Leibniz’s Law must be abandoned or sufficiently reworked to allow for this kind of status change. It is granted that Leibniz’s Law is meant to apply only to objects that are strictly numerically identical. This, however, should not change our perspective on its bearing on the doctrine of the Incarnation, as tradition has held that God the Son and Jesus of Nazareth have had that strict numerically identical relationship. But if this is true, then what are we to make of the fact that the pre-incarnate God the Son and the incarnate Jesus of Nazareth hold two different sets of properties, the difference between those sets being those properties that accompany being embodied? If Leibniz’s Law is true, a contradiction cannot help but arise between those propositions that affirm both the numerical identity and differing properties of Jesus of Nazareth and God the Son.

It is at this point that we must specify what it is exactly that is being identically preserved in the Incarnation between the pre-incarnate God the Son and Jesus of Nazareth. As has been said, it is obviously true that the sum total of all the properties of God the Son and Jesus of Nazareth differ greatly. However, if we were to restrict the numerical identity of the pre-incarnate God the Son and the incarnate Jesus of Nazareth to the person who is both, the contradiction found in subjecting the proposition ‘God the Son = Jesus of Nazareth’ to Leibniz’s Law disappears. No longer are we holding that the sets of the sum totals of all the properties held by the being that is the pre-incarnate Son of God and the being that is the incarnate Jesus of Nazareth are one and the same, but rather that the sets of the sum totals of all the properties of the person that is both the pre-incarnate Son of God and incarnate Jesus of Nazareth are one and the same. When this version of the doctrine is examined, one will find that it is exactly that which is affirmed by orthodoxy. In becoming the incarnate Jesus of Nazareth, the person of the God the Son took on human nature in addition to his divine nature, thereby acquiring those new properties of humanity while retaining those properties of the divine nature, as well as those of his person, God the Son. This is affirmed all while still affirming the truth of Leibniz’s Law and avoiding the pitfalls of the theory of relative identity, simply by restricting the set of identical properties in God the Son and Jesus of Nazareth to that of personhood.

I believe that Morris assumes something like this in this section of his book, but he does not explicitly state anything like it, thus leading to my treatment of what appeared to be a contradiction. Indeed, when he says, “The only purpose of denying indiscernibility would be to all that there are some properties Jesus had but God the Son lacked, and vice versa,” this must be the case, for such an obvious distinction between God the Son pre-incarnate and incarnate could not have actually escaped his careful and watchful eye.