Thursday, December 13, 2007

Long snakes and Relativity Theory

This is an exercise in some rather gruesome metaphysics of parthood. If you don't like gruesome examples, stop reading. There will be a payoff, though--a defense of animalism.

Imagine a long snake, all stretched out, and for simplicity assume uniform linear mass distribution. Let's say the length of the snake is 10 meters and its diameter is 0.1 meters. Suppose that something cuts off the rear 1/4 of the snake, and the cut happens at near-light speed--maybe a blade descends on the poor snake at 90% of the speed of light. Suppose that almost instantaneously before the blade touches the unfortunate snake, a butterfly almost instantaneously brushes its wing against the tip of the snake's tail and never has any other contact with the snake or its bits. (Let's say "almost instantaneously" means "in the amount of time during which light travels 0.01 meters.) Then, it seems, butterfly touched the snake. Call the reference frame in which the above description takes place "frame A". But, it is a fact that then there is a reference frame, call it "frame B", in which when the butterfly touched the snake, the tail was already cut off. It seems that in this reference frame, the butterfly did not touch a (or the) snake--he merely touched a cut-off tail.

It follows that the following propositions cannot all be true:

  1. In frame A, the butterfly touched the snake.
  2. In frame B, the butterfly did not touch the snake.
  3. Whether two substances touch does not depend on the reference frame.

So we must deny at least one of (1), (2) or (3). Note that affirming (1) and (2) and discarding (3) would have the interesting consequence that whether battery has been committed depends on the reference frame. For suppose that an accident cuts off my leg at near light speed. Then there can be a situation where you very quickly mutilate the "foot" at the end of that leg (I put it in quotation marks, because there is an issue whether a disconnected foot is a foot) just before the leg is cut off. By exactly the same reasoning, then, in one reference frame it seems you've committed battery--you've mutilated a part of me--and in another you haven't. (In neither reference frame do I feel the mutilation, because the leg is cut off before the nerve signals come from the "foot" to my central nervous system.) I don't think whether battery has been committed should differ between reference frames. (Would you be guilty in one frame and innocent in another?)

So, I need to reject either (1) or (2) or both. It seems to me that (1) is harder to deny than (2). To deny (1) we would have to allow that the tail is fully connected to the snake, and yet not a part of it because it is about to be cut. So, we should deny (2). Hence, something can be a part of a body even though it is already severed from the body.

How long can this weird state of affairs go on? I don't really know. We could say that it goes on until the part is severed in all reference frames. But while that is an attractive idea, it neglects the fact that we are talking about organic parts, and what matters here is organic connections, not relativistic connections. The relevant scale of velocities is the speed of the fastest organic signals, not the speed of light. Suppose that the snake's brain sent a nerve signal to the tip of the tail, and the nerve signal passed the cut-point just before the cutting began. Because nerve signals move much slower than light, before the nerve signal arrives at the tip of the tail, it will already be the case that in all reference frames the tail is severed. Still, I think the tail might count as part of the snake, as long as the signal is traveling there. Let's say the signal tells the tip of the tail to wiggle. Maybe we can say that while the tail yet wiggles under the influence of that nerve signal, the tail is a part of the snake.

Does any of this matter, except as abstruse metaphysics? Maybe. Take animalism, the theory that you and I are animals. A standard objection to animalism is that we can survive as brains in a vat, but a brain in a vat is not an animal. However, the above considerations suggest that, at least for more complex beasts like snakes and humans, connection to the nervous system has a relevance to determining what still is and what no longer is a part of the body. The nervous system, then, has a kind of centrality in more complex animals from the organic point of view. And this makes it plausible the animal could survive as an organism when pared down to just a nervous system, assuming appropriate life-support mechanisms. And it is not a far leap from that to suppose that we can survive as organisms with just central nervous systems, and maybe even with just the central part of the central nervous system, namely the brain (in a vat, of course).

Now, if animalism is true, then we were all once fetuses--I was the numerically same organism as a fetus. Thus, a human fetus is one of us, and presumably killing it is wrong. Thus, we have here a loose line of argumentation from Relativity Theory to the wrongness of abortion. Isn't philosophy fun?

5 comments:

chauncey said...

1. A detached finger may still be mine even if the finger ceases to move under the influence of a nerve signal sent before the severing. It's mine in the sense that I would rush to the hospital and insist that they try to reattach it, etc. This "being mine" relation is surely familiar and differs from your "being part of" relation. Question: if something touches a detached part of me--touches a detached finger that's mine--has it touched me? Here's one reason to think so: I might have all kinds of interesting cogntive/emotional reactions to such touching even if knowledge of the touching is only available to me via visual or verbal reports. But this points to a way in which such a touching is not a touching of me: I can't have "direct" knowledge of the touching. But direct knowledge is problematic here: local numbing can keep me from having knowledge of being touched when a part is attached.

So, I think there are other kinds of reason for denying your 2, but I think it involves changing the relation of interest--from "being an organic part of" to "being mine". (Of course, my kind of reason doesn't obviously help with your larger argument.)

2. You write, "the above considerations suggest that, at least for more complex beasts like snakes and humans, connection to the nervous system has a relevance to determining what still is and what no longer is a part of the body." How does the argument for this go? You suggested the nerve-impulse story as a way of tolerating the denial of your 2. So is this something like an inference to the best explanation?

Alexander R Pruss said...

1. That's an interesting reading of the situation. Yes, I think you're right about the emotional reactions here. This is also related to the way a visually impaired person might feel about a stranger's touching her seeing eye dog--it's inappropriate in rather the way that touching the person would be inappropriate.

For me, "being an organic part of" is the relation of interest, but that's because that is a very weighty relation on my view. The "being mine" relation you're describing is, I think, analogous to the stronger one.

2. I don't know the form of argument I used here. Arguments whose steps make use of the inference "p suggests q" are pretty weak (I am not claiming much strength of argument here). It may simply be that if we accept p, our intuitions will be modified in such a way that q will be plausible?

3. Here's another case. The finger is cut off. I sell it. (Nevermind whether it is moral to buy and sell body parts; whether or not one this is morally licit, it is surely possible at least in some jurisdications.) How should I feel about its being touched then? No intrinsic change happened here...

Alexander R Pruss said...

I meant: no intrinsic change happened in the sale. (I take it that sale does not intrinsically change objects, though it changes various normative facts.)

chauncey said...

1. Let me add some elements to the case. I voluntarily have my finger cut off. (I don't have to be the one that does it.) I then voluntarily sell it. (Did I cut it off in order to sell it?) And then the finger is touched. How should I feel?

It seems to me that being prepared to part with one's own finger by selling it suggests a preparedness to drop entitlement to various things that go on with it. I might in fact feel a certain way when that sold finger is touched, but a friend might say that I shouldn't feel that way OR that I shouldn't have sold it. In a slogan: by selling the finger, I disown it.

But I think that's too strong for surely there are cases of selling that don't entail "disowning" the propriety of various reactions to things that happen to the thing sold. An act that is sufficient for relinquishing a thing (a part of oneself) in the marketplace need not be sufficient for genuinely disowning that thing (that part of oneself).

2. Without going into details, I think there is an interesting connection here with cases of giving up an infant for adoption.

3. I'm inclined to think the being an organic part of relation is among the things one might point to in justifying a "mine" claim or reaction.

Alexander R Pruss said...

That's interesting. Your normative approach is illuminating here.

Notice that it is not just the voluntary removal and selling as such that leads to the disowning. For if out of poverty I have my finger removed and sold, I might well appropriately feel of the finger as if it were mine, and there may, thus, be a normative, non-legal, and not parthood-involving sense in which the finger still is mine. The finger may be long to the buyer in the legal sense, but until it is attached to the buyer, it does not belong to the buyer in this particular way.

I wonder if one could take some of these considerations and build them into a case against buying organs from those who are forced by poverty to sell their organs. (That's a tough question.)