Two Problems concerning Divine Immutability and the Incarnation Michael Gorman Introduction Central to the Christian message is the proclamation that the Second Person of the Holy Trinity, the Son, became human for our salvation. But also central to Christianity is its understanding of the divine nature, an understanding that has traditionally included the idea that God is immutable. There are some tensions here. At least at first glance, the doctrine of divine immutability raises problems for the doctrine of the Incarnation. If Christ is divine, and therefore immutable, how can he go through changes, such as walking down the street or being nailed to the Cross? And there is a prior difficulty: if the divine persons are immutable, how can a divine person have become incarnate in the first place? Mutability, Immutability, and the Incarnate Word We can think of the first difficulty as taking the following form. On the one hand, it seems right to say that Christ is divine and that everything divine is immutable, and from these, it would seem to follow that Christ is immutable. On the other hand, it seems right to say that Christ changes, as the Gospel accounts show him walking, becoming sad or angry, and so forth. But how can Christ be both something immutable and something that changes? [End Page 899] One possible way of solving the problem is as follows. I call this solution "Tomeistic" because it draws inspiration from the so-called Tome of Pope Leo, a work incorporated into the acts of the Council of Chalcedon in 451. Tomeistic Christology, in a rough-and-ready version, looks something like this.1 Christ is one person with two natures. Some things are true of his human nature, while others are true of his divine nature. For example, his human nature is mutable, while his divine nature is immutable. Is he, Christ himself, both mutable and immutable? Yes. He is mutable insofar as that means he has a nature that is mutable, and he is immutable insofar as that means he has a nature that is immutable. Those specifications of what "mutable" and "immutable" mean are important. "He is mutable and immutable" might sound contradictory, but on the Tomeistic understanding, it is not: when it is said that Christ is mutable, what is meant is that he has a nature that is mutable, and when it is said that he is immutable, what is meant is that he has a nature that is immutable. There is nothing contradictory about that. I am bringing up Tomeistic Christology mostly so it can serve as a contrast with the position I will myself be taking. Although I cannot here give anything like a full account of what is wrong with the Tomeist view, I can at least convey the gist of my concern by saying that I think it bad metaphysics. Natures are not mutable or immutable, and thinking otherwise is a category mistake. Things, substances, are mutable or immutable. If there is any sense to saying that a nature is mutable or immutable, it is this: a nature is mutable or immutable insofar as it is a principle in virtue of which this or that substance is mutable or immutable. Nor is the point restricted to the case of mutability and immutability. It is true pretty generally of features that they are had by substances, not natures, and likewise true pretty generally of actions that they are performed by substances, not natures.2 Natures are not the bearers of features or the performers of actions so much as they are principles in virtue of which substances [End Page 900] have features, perform actions, and so on. A nature is a principium quo, not a principium quod.3 If this approach is problematic in the way that I have suggested, what would be a better one? The first thing to do is to reverse the priorities of Tomeism and put substance (person) into the driver's seat, where it rightly belongs. Instead of saying that Christ's human nature is mutable and that his divine nature is immutable, let us accept that, if anything here is mutable or immutable in the...