Thursday, March 2, 2023

Causing via a part

Assume this plausible principle:

  1. If a part x of z causes w, then z causes w.

Add this controversial thesis:

  1. For any x and y, there is a z that x and y are parts of.

Thesis (2) is a consequence of mereological universalism, for instance.

Finally, add this pretty plausible principle:

  1. All the parts of a physical entity are physical.

Here is an interesting consequence of (1)–(3):

  1. If there is any non-physical entity, any entity that has a cause has a cause that is not a physical entity.

For if w is an entity that has a cause x, and y is any non-physical entity, by (2) there is a z that x and y are both parts of. By (3), z is not physical. And by (1), z causes w.

In particular, given (1)–(3) and the obvious fact that some physical thing has a cause, we have an argument from causal closure (the thesis that no physical entity has a non-physical cause) to full-strength physicalism (the thesis that all entities are physical). Whatever we think of causal closure and physicalism, however, it does not seem that causal closure should entail full-strength physicalism.

Here is another curious line of thought. Strengthen (2) to another consequence of mereological universalism:

  1. The cosmos exists, i.e., there is an entity c such that every entity is a part of c.

Then (1) and (5) yield the following holistic thesis:

  1. Every item that has a cause is caused by the cosmos.

That sounds quite implausible.

We could take the above lines of thought to refute (1). But (1) sounds pretty plausible. A different move is to take the above lines of thought to refute (2) and (5), and thereby mereological universalism.

All in all, I suspect that (1) fits best with a view on which composition is quite limited.


Fr M. Kirby said...

It's probably my intellectual limitatins, but I would find the argument easier to follow if you had not used x, y and z in both the first premises. I think I get it now, but at first I couldn't get past the first two premises, trying to work out how they related to one another.

Would a re-expression be useful, or am I missing the point somehow?

Fr M. Kirby said...

Ah, referring to my intellectual limitations with an obvious typo. Brilliant.

BTW, should one of the zs been a w?

Alexander R Pruss said...

Fr Kirby: That's actually a really good stylistic point. Keep the letters in the statement matching the letters in the application so one doesn't have to keep a translation list in the mind. I think it should be better now. I usually try to pay at least a little attention to this when writing up mathy stuff.

Atno said...

"All the parts of a physical entity are physical."

It does seem pretty plausible at first glance. But it's common for Aristotelians to say human beings are physical entities, but have a non-physical (or transphysical, or spiritual) part in the soul that allows for intellect and will, etc.
What should we say to that?

Alexander R Pruss said...

I'd say that human beings aren't physical entities.

A more worrisome thing is that on an Aristotelian view I don't know that any substance is a physical entity. For form does not seem to be a physical entity and is a part of any substance.

I wonder if we shouldn't say that at some point the physical/nonphysical distinction breaks down. Consider trope theory, and suppose that an electron has a charge trope. Is the charge trope a physical object? I don't know.