Thursday, May 15, 2008

Livers, brains, conscious computation and teleology

Let us suppose, for the sake of exploration the following (false) thesis:

  1. I am conscious because of a part of me—viz., my brain—engaging in certain computations which could also be engaged in by sophisticated computers, thereby rendering these computers conscious.
I will also assume the following, which seems obvious to me, but I think in the end we will find that there is a tension between it and (1):
  1. The brain and liver are both proper parts of me.
Call the kinds of computations that give rise to consciousness "C-computations". So by (1) I am conscious because of my brain's C-computations, and if my laptop were to engage in C-computations, that would give rise to consciousness in it.[note 1]

Now, let us imagine that my liver started doing C-computations within itself, but did not let anything outside it know about this. Normally, livers regulate various biochemical reactions unconsciously (I assume), but let us imagine that my liver became aware of what it was doing through engaging in C-computations on the data available to it. Of course, livers can't willy nilly do that. So, part of my supposition is that the structure of my liver, by a freak of nature or nurture, has shifted in such wise that it became a biochemical computer running C-computations. As long as the liver continued serving my body, with the same external functions, this added sophistication would not (I assume) make it cease to be a part of me.

So now I have two body parts where C-computations go on: my brain and my liver. However, the following is very plausible to me:

  1. Whatever computations my liver were to perform, I would do not have direct awareness of what is going in my liver, except insofar as the liver transmitted information to its outside.
In the hypothesis I am considering, the liver "keeps to itself", not sending data into my nervous system about its new computational activities. So, I submit, I would not be aware of what is going on there. Thus, there would be consciousness, since there would be C-computations, but it would not be consciousness that I have.

But now we have a puzzle. In this setup, I am conscious in virtue of the neural computations that my brain engages in, but am not conscious in virtue of the hepatic computations that my liver engages in. Thus, when my neural computation is quiescent due to sleep, but my hepatic computation continue, I am, simpliciter, not conscious. Why? After all, both the brain and the liver are parts of me. The brain also "keeps to itself": it only lets the rest of the body have the outputs of its computation, but the details of it, it keeps to itself, just as in my thought experiment the liver does. The idea in (1) seemed to have been that computational activity by an organic part of me would give rise to consciousness that is mine. But by the same token the hepatic computational activity should give rise to consciousness that is mine.

So what should someone who accepts (1), (2) and (3) (and the various subsidiary assumptions) say about this? Well, I think the best thing to do would be to abandon (1), denying that I think in virtue of computational activity. A second-best solution would be to qualify (2): yes, the brain and the liver are parts of me, but the brain is a more "intimate" or "central" part of me. But note that one cannot explain this intimacy or centrality in terms of the brain's engaging in computational activity. For the liver could do that, too. Could one explain it in terms of how much coordinating the brain actually does of my bodily functions, both voluntary and not? Maybe, but this has to be taken teleologically. For we can imagine as part of the thought experiment that I become paralyzed, and my brain no longer coordinates my bodily functions, but they are in fact coordinated by medical technology. So the defender of (1) who wishes to qualify (2) in this way may have to embrace teleology to account for the difference between the brain and the liver.

But there may be another solution that doesn't seem to involve teleology. One might say that each bundle of C-computational activities gives rise to a conscious being. Thus, perhaps, in my thought experiment, there are two persons, who contingently have all of their parts in common: (a) the neural person that I am, and (b) the hepatic person that I am not. Contingently, because if the liver were replaced by a prosthesis that maintains basic bodily functions, (b) would die, but (a) would continue to exist, while if the brain were replaced by such a prosthesis, (a) would die, but (b) would continue to exist. This view can be seen as a way of qualifying (2): yes, both the brain and the liver are parts of me, but one is an essential part and the other not. On this view, the claim is that:

  1. I am conscious in virtue of C-computations in an essential part of me.
But actually further qualification is needed. For suppose that instead of my liver becoming conscious, one of my neurons were to suddenly complexify immensely, while retaining the same external functions, so that internally it was engaging in sophisticated C-computations, while externally it worked like every other neuron. It seems that an analogue to (3) would still hold—I wouldn't be aware of what the neuron is aware of (but I admit that my intuition is weaker here). And so (4) is false—for the C-computations in the neuron are computations in the brain, and the brain is an essential part of me, but I am not conscious in virtue of them.

It is difficult to fix up (4). One might require that the computations take place throughout the whole of the essential part. But supposing that for a while my left brain hemisphere fell asleep while the right continued C-computing (dolphins practice such "unihemispheric sleep"), then the computations would not be taking place throughout the whole of the essential part. But I would, surely, still be aware. I am not sure there is any way of fixing up (4) to avoid the conscious-neuron and unihemispheric sleep counterexamples. If not, and if no other two-persons-in-one-body solution can be articulated, then the teleological solution may be needed.

Final remarks: I think naturalism requires something like (1). If so, then given the plausibility of (2) and (3), naturalists need to accept teleology. But teleology does not fit well into naturalism. So naturalism is in trouble.


Anonymous said...

I hate to break it to you, but you aren't aware of what is going on in most of your mind, with or without a conscious liver.

Tanasije Gjorgoski said...

The problem I guess is that once we want to equate "me" with the body (and talk about 'brain' as part of myself), and on other side we are inclined to discuss this "conscious me" as a product of (or being identical with) the brain. So, there is a tension between those two.
But seems to me naturalists, can just say that there are two senses of "me" that we should distinguish: me-body and me-consciousness , and say that me-consciousness is what is product of (or identical with) the brain, but that me-consciousness wrongly treats me-body as identical to itself.

So naturalist can say, that if you are talking about me-consciousness when using "me", it is simply wrong to say that brain is part of me. But if by "me" we are talking about our body (which we consistently can claim to be "ours" not in terms of identity, but in terms of ownership), brain IS part of me.

Alexander R Pruss said...


One problem is that for ethical applications, we need to hold on to both intuitions together. Certain actions done to my body have the moral character they do because both the body is at least a part of me, and I am a person. (These actions do not have the same character when done to a body that is merely owned by me--say, the body of my dog--nor do they have the same character when done to a body that is at least a part of a non-person.) And it is crucial for this that the "me" and the "I" be the same.

If we abandon the naturalism and accept hylomorphic dualism, we can hold on to both intuitions. We can, though less well, hold on to both if we accept Cartesian dualism but manage somehow to resist the identification of the self with the soul, instead identifying the self with the soul-body whole.