I have been spending some time working through the doctrine of the Incarnation and as such have been spending a great deal of time in Tom Morris's The Logic of God Incarnate. There are a number of questions that I plan to post on beginning with this post about reduplicative statements and Morris's two minds view.
I think most people who have brushed up against the doctrine of the Incarnation have probably heard some form of the reduplicative move. Reduplicative statements are supposed to block contradictions by showing that the Incarnate God held contradictory properties qua his two natures. These statements take the form of 'x qua A is N' or 'x as A is N.' Morris seems, rightly I think, to want to reject the reduplicative move because it is vulnerable to the rather serious objection that reduplicative statements result in saying that a subject holds a property and its logical compliment. The objection is that if we consider a conjunctive reduplicative proposition of the form 'x as A is N and x as B is not N' then the result is that x is both N and not N.
"If the subjects of the conjuncts are the same and the substituends of N are univocal across the conjunction, then as long as the reduplication predicates being A of x and predicates being B of x, and being N is entailed by being A, and not being N is entailed by being B, then the reduplicative form of predication accomplishes nothing except for muddying the waters, since in the end the contradiction stands of x being characterized as both N and not N." (TLGI 48,49)
So reduplicative statements such as, "Jesus Christ qua his divine nature never came into existence, but Jesus Christ qua his human nature did come into existence" would entail the one person, Jesus Christ, both did and did not come into existence. I think Morris is right about muddying the waters, and I don't see how reduplicative statements can free orthodox Christology from the charge of contradiction.
Morris does a nice bit of work arguing that we should consider natures as natural kinds. In which case it might not be impossible for something to belong to more than one natural kind. This account of natural kinds seems to be a good answer to the two natures problem that avoids the reduplicative move. However, when Morris gets to the two minds portion of his defense he brings the reduplication move back into the argument. Morris states that God qua his divine mind cannot be tempted, but God qua his human mind can be tempted. If the reduplicative objection holds then it results in God being both temptable and not temptable. We might also add that the statement could be formed such that God is both omniscient and not omniscient. If this is the case then Morris's defense fails to rescue the doctrine of the Incarnation form the logical incoherence charge.
