Saturday, September 7, 2019

Substances are not parts of substances

Here is a quick and simple argument for the Aristotelian axiom that substances are not parts of substances.

  1. The parts of substances are at least partly grounded in the substances.

  2. Substances are not even partly grounded in other things.

  3. Therefore, substances are not proper parts of other substances.

I suppose (1) is probably just as controversial as (3).


Jonathan D. Jacobs said...

If we add the premise 2 the claim that 4) dependence entails grounding and the claim that 5) everything depends on God, you get the claim that 6) only God is a substance. So do you accept 6 or reject 4?

Alexander R Pruss said...

Good point!

It's not clear that causal dependence entails grounding, or even partial grounding. But I do see the pull to the thought that God partially grounds our existence. Whether that implies that he partially grounds us is not completely clear, but is plausible, isn't it?

Jonathan D. Jacobs said...

Seems plausible to me. If we accept that only God is a substance, then the force of the conclusion is dramatically weakened. If we don't, then it looks like we have to deny that God at least partially grounds us. Alternatively, we could just allow that substances can be parts of substances. I'm inclined toward the later.

Alexander R Pruss said...

But if we allow substances to be partly grounded in other substances, then it's really hard to distinguish substances from accidents.

Jonathan D. Jacobs said...

If you are a pluralist about part, you can distinguish the substances that are a part of a substance from the non-substances by appeal to different part-whole relations (like, say, Armstrong). Alternatively, if you are a pluralist about being, you can distinguish them by their mode of being. But if you deny both forms of pluralism, then, yes, you will have some difficulty there. Do you deny both forms of pluralism?

Alexander R Pruss said...

Unless your analysis of the relevant part-whole relation or of the mode of being involves the difference between being self-grounded and having grounds in another.

Both pluralisms may be OK, but one needs an account of the different kinds of part-whole relation or the different modes of being. And it would be circular to say, for instance, that substances are the things that have the substantial mode of being.