How do we get to an unmoved mover?

I just realized that there is a difficulty in Aquinas’ First Way that I think hasn’t been noted, which builds on the difficulty noted yesterday.

Put the First Way in the following simpleminded way, which I think captures the central ideas:

1. Causes of change are either passers-on of change or originators of change.

2. It can’t be that the causes of change are all passers-on of change.

3. So there must be an originator of change.

4. And this is an unmoved mover (or, more precisely, unchanged changer).

There is a fair amount of detail one can fill in to argue for (2), but that’s not what I want to focus on. I want to focus on the move from (3) to (4).

What licenses us in thinking that an originator of change is itself unchanging?

The idea seems to be that if a cause of change is itself changing, then it is merely a passer-on of change. But this need not be. In my previous post, I imagined an unchanging and timeless demiurge endowed by God with the power to originate change, and noted that in that scenario the demiurge is an unmoved mover but isn’t God.

But now let’s build up and modify my demiurge story. First, let’s be concrete about what motion the demiurge causes. The demiurge has been gifted by God with the power to directly will Bob to rotate around a fixed axis, and the demiurge changelessly exercises this power. (Maybe Bob is one of the Aristotelian heavenly spheres). Second, let’s specify that the demiurge, albeit unchanging, is in time and has an unchanging body in addition to a mind and will. If we can’t have a changeless thing in space and time, don’t worry about it. The third step will fix that. The third step is this. The demiurge itself is caused by God to slowly orbit the sun in a way that the demiurge does not notice.

Thus, we have a demiurge with a mental power to make Bob rotate, and the demiurge exercises this mental power changelessly. At the same time, and completelessly coincidentally to the demiurge’s exercise of the mental power to make Bob rotate, the demiurge orbits the sun.

The demiurge is thus a moved mover. But it is also an originator rather than passer-on of change. In Aristotelian terminology, the demiurge is a moved mover per accidens: its own movement around the sun is coincidental to its origination of Bob’s axial rotation.

We cannot, thus, assume from the existence of an originator of change that there is an unmoved mover.

Does Aquinas have the resources to fill in the gap? Of course, if the (accidentally) moved originator of change coming out of step (3) of the argument is itself changing, that change has to have a cause, and we can then run the argument again. If we can rule out an ungrounded infinite sequence of accidentally moved originators of change—ones that like our demiurge happen to be moving in one respect but produce change by a coincidental exercise of power—then we can get to a genuinely unmoved mover.

But Aquinas’ main tool for avoiding regresses in cosmological arguments is the idea that there cannot be an infinite regress in a per se causal sequence. And while there are complications in the notion of a per se causal sequence, I think it is pretty clear that the sequence I am imagining is not a per se causal sequence. The demiurge’s moving of Bob is coincidental to the demiurge’s own motion. Suppose that a demiurge makes Bob spin by an unchanging exercise of a mental power, and a tetartourge by an unchanging exercise of a mental power makes the demiurge coincidentally slowly orbit the sun while the tetartourge coincidentally orbits the moon. Then the tetartourge is not a cause of Bob’s motion. But in a per se causal sequence we have transitivity: the earlier items are always causes of the later ones. So this is not a per se causal sequence.

Of course, we might ask what explains the demiurge’s (and tetartourge’s) possession and exercise of the mental power to make something else move. But now we are deviating from the First Way: we are asking for explanations of something other than change. I think one can fill this in, by an argument about causation and regresses rather than change and motion. But if we do that, then the stuff about change and motion that is at the heart of the First Way can simply drop out.

I titled my previous post “An easily patched hole in the First Way”. But I think I was too glib there, too. In that context, too, I think one needs to go beyond the resources of the First Way to patch the hole.