Assume this plausible principle:
- If a part x of z causes w, then z causes w.
Add this controversial thesis:
- 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:
- All the parts of a physical entity are physical.
Here is an interesting consequence of (1)–(3):
- 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:
- 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:
- 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.
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.
ReplyDeleteWould a re-expression be useful, or am I missing the point somehow?
Ah, referring to my intellectual limitations with an obvious typo. Brilliant.
ReplyDeleteBTW, should one of the zs been a w?
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.
ReplyDelete"All the parts of a physical entity are physical."
ReplyDeleteIt 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?
I'd say that human beings aren't physical entities.
ReplyDeleteA 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.