Monday, October 31, 2022

Transsubstantiation and magnets

On Thomistic accounts of transsubstantiation, the accidents of bread and wine continue to exist even when the substance no longer does (having been turned into the substance of Christ’s body and blood). This seems problematic.

Here is an analogy that occurred to me. Consider a magnet. It’s not crazy to think of the magnet’s magnetic field as an accident of the magnet. But the magnetic field extends spatially beyond the magnet. Thus, it exists in places where the magnet does not.

Now, according to four-dimensionalism, time is rather like space. If so, then an accident existing when its substance does not is rather like an accident existing where its substance does not. Hence to the four-dimensionalist, the magnet analogy should be quite helpful.

Actually, if we throw relativity into the mix, then we can get an even closer analogy, assuming still that a magnet’s field is an accident of the magnet. Imagine that the magnet is annihilated. The magnetic field disappears, but gradually, starting near the magnet, because all effects propagate at most at the speed of light. Thus, even when the magnet is destroyed, for a short period its magnetic field still exists.

That said, I don’t know if the magnet’s field is an accident of it. (Rob Koons in conversation suggested it might be.) But it’s comprehensible to think of it as such, and hence the analogy makes Thomistic transsubtantiaton comprehensible, I think.


SMatthewStolte said...

But where in space is the substance of the magnet? I would have thought that it is where it acts, and since the magnetic field is how the magnet acts qua magnet, it could not extend beyond the substance. The reason it feels like the magnetic field extends beyond the magnet is that it acts in more than one way (in the way it acts on the hand when it is held and in the way it acts on magnetic metals).

Alexander R Pruss said...

Imagine that there is only one substance in the world, a magnet. It has a magnetic field extending around it, beyond the magnet, no?

(Of course, one could count the magnetic field as a separate substance. But it's not clear that that's the right view.)

SMatthewStolte said...

No, I don’t think so. I mean, I think that in most contexts, it would be fine to say that there is a single, cube-shaped lodestone (1×1×1) and a field that extends beyond it. But I have real doubts that this way of talking works here.

Here is an analogy. The question of where I am could be taken to be asking either where my principal activity takes place or else where all of my activities take place. According to the first way, I am where my brain is. According to the second way, I am where my entire body is. But it is the latter, holistic answer, that is more fundamental.
On this analogy, the cube-shaped lodestone is like the brain; its magnetic field is like the whole body. The substance as a whole has one small, localized activity and another activity that is more spread out. The answer to the question, “Where is the magnet?” depends on which activity you have in mind, but the more fundamental version of the question concerns all of its activities rather than some of its limited, localized activities.

What am I missing? How else does a substance get its ‘where’?