Saturday, December 20, 2014

Are parts modes?

There are two variations on Aristotelian ontology. On the sparser version there are substances and their modes (accidents and essences). On the more bloated version there are substances, modes and (proper) parts. I want to argue that the more bloated version should be reduced to the sparser one.

Parts in an Aristotelian ontology are unlike the parts of typical contemporary ontologies. They are not substances, but rather they are objects that depend on the substance they are parts of. At least normally when a part, say a finger, comes to be detached from the substance it is a part of, it ceases to exist—a detached finger is a finger in name only, as Aristotle insists.

This makes the parts of Aristotelian ontology mode-like in their dependence on the whole. Ockham's razor then suggests that rather than supposing three fundamental categories—substances, mode and parts—we will do better to posit that a part is just a kind of mode. Thus, I really do have a heart, but my heart is just much a mode or accident of me—my cardiacality—as my knowing English is. Both my heart and my knowledge of English confer on me certain causal powers and causal liabilities (knowing English makes me liable to having my feelings hurt by uncomplimentary assertions in English!)

This is not an elimination of parts. Some of my accidents are parts and others are not. Which ones? I do not know. Maybe those accidents that occupy space are parts and those accidents that do not are not. My knowing English doesn't occupy space, while my cardiacality is somewhat vaguely but really located located in space.

Perhaps we need a finer distinction, though. Consider the strength of my arm. This isn't a part of me, but it seems to be located in my arm. I suggest that we distinguish between three ways that a mode can get a location. It can (a) inherit a location from a subject, or (b) it can inherit a location from its own modes, or (c) it can be located in its own right. I suggest that a mode is a part if and only if it has a location of type (b) or (c). The strength of my arm inherits its location from its subject—my arm—and hence is not a part. (It's important to the full development of this ontology that modes can nest. Thus, my arm is a mode of me, and the strength of that arm is a mode of this mode. Both I and my arm are subjects of the strength of the arm.)

I think the distinction between type (b) and type (c) parts is worth thinking about. Maybe matter, that mysterious ingredient in Aristotelian ontology, can be identified with type (c) parts?

6 comments:

William said...

The problem with calling body parts modes is that it makes organ transplantation a miracle. Centuries ago, this kind of reasoning would likely have predicted that heart transplantation could never occur without a miracle: the heart could never function as a heart in the absence of its (original) body. So, apply modus tollens...

Alexander R Pruss said...

Good point. But heat is a paradigm mode, and can be transplanted. :-)

Heath White said...

I would have thought that this idea of parts means that a “part” is really whatever fulfills a certain function, and there would be no problem with organ transplants because the function is multiply realizable. E.g. right now my (organic) heart supplies my cardiacality, but were I to get an artificial heart then that piece of plastic (or whatever) would supply my cardiacality and therefore it would be my heart. My excised organic ex-heart would be just that.

Alexander R Pruss said...

Note that if one takes this view, and one accepts the Catholic view that the accidents of bread and wine persist after transubstantation, then one needs to say that the Church meant by "accidents" modes that aren't also parts. This seems reasonable.

Ben Koons said...

What about the case of a plant that can be naturally divided into two plants? It seems that each part of the initial plant was potentially a whole plant, but modes aren't potentially substances. Also, in the case of grafting two plants together, we have a substance becoming the mode of another substance.

Alexander R Pruss said...

Rob Koons and I have been speculating that a form might change between being substantial and being accidental. For instance, when a particle exists outside of a living organism, it has a substantial form. That form is a mode of it (modes can be essential or accidental). Perhaps that mode can come to be an accidental mode of a living organism when the particle is eaten. And then upon excretion, the mode can become substantial again. The *substance* that the particle is does not exist when the particle is accreted into the organism, but something of that substance--namely, its form--does exist.

Perhaps a similar story could be told about the plant. The plant has two accidental modes, and is capable of perishing in such a way that the two accidental modes become the substantial modes of two new substances.

That said, this is highly speculative and I do not want to commit to it. But if one takes seriously the possibility of modes existing after their substance has perished (as in the Eucharist), then this speculation becomes more plausible.