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Friday, November 18, 2011

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Hi Bill, and thanks for taking this up again. I remember disputing this with you at your Powerblogs site, long ago.

The distinction you make about the pure mysterian position is clarifying. I must say, though, that I find it hard to understand why anyone would commit to such a stance. McGinn may well be right about this one really being forever beyond us, but I can't imagine how he or anyone else could know that.

You wrote:

How do we know it is nonsense? We know this by thinking attentively about colors and sounds and by grasping that a color is not the sort of item that could be a sound.

But no amount of thinking attentively about the human brain is sufficient for this, because we flatter ourselves too much if we think we know exactly what consciousness is and how it arises, or that we know enough about the physical world-system to list with exhaustive certainty what effects it can and can't produce. (After all, long ago we might have denied with equal confidence that a 'merely' physical system could defeat a master at chess, or that a flat black box, small enough to fit in the palm of your hand and with no visible connection to any external object, could produce an immediate effect on the other side of the world.)

If you protest that consciousness, being immaterial, is different in kind from these examples, the materialist will reply that the aspects of the physical world that now allow us to call Hong Kong with our cell phones would long ago have seemed quite immaterial too. If you respond that consciousness differs further in that it is purely subjective, the materialist will ask just how you can be so sure that it is downright impossible for any physical system to instantiate subjective awareness, given our non-exhaustive understanding of the physical world. If after that you simply insist that it is just obviously so, then the materialist will say "Well, it isn't obvious to me; you're just asserting what you had sought to demonstrate."

On the other side of the balance, there are many good reasons to suspect that the conscious mind really is the product of the brain's activity: we see that various mental states can reliably be induced by stimulating particular regions of the brain, that consciousness and its contents can be altered (or even deleted and restored) by changing the physical state of the brain mechanically or chemically, etc.

It is certainly true that so far we have no idea at all how matter can possibly give rise to subjective consciousness; we can't even imagine what a physical theory of consciousness would look like. But a proposition like "some physical systems are conscious" (I hope it is not a digression to focus on consciousness rather than intentionality here) hardly strikes materialists as obvious nonsense. It may of course be false, but to insist that it is not even comprehensible -- that it is on all fours with something like 'Quadruplicity drinks procrastination' -- assumes, I think, knowledge about the ontology of consciousness, and about the limitations of the physical world, that we simply don't have.

Your last paragraph sharpens the question very nicely:

The deep underlying issue here seems to be this: Is our inability to understand how such-and-such is broadly-logically possible a sufficient reason for denying that such-and-such is objectively broadly-logically possible? To put it another way, the issue is whether there could be true mysteries, where a mystery is a proposition that by our best lights must appear either to be or to entail a broadly-logical contradiction.

To the materialist, then, a conscious brain entails no broadly-logical contradiction: it confronts us, instead, with our ignorance, with the limits of our understanding. To the non-mysterian, this ignorance may or may not be remediable; there is simply no way for us to know.

Do forgive me for the length of this comment. I know pith is paramount here at MP.

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