Wednesday, April 18, 2007

A good Vallicella post on explaining consciousness


Blue Devil Knight said...

But there is an important distinction to be made between the felt temperature — the sensory quale, the Feiglian 'raw feel', the Nagelian 'what it is like' — and the temperature as a purely physical attribute. Physics studies the latter but has nothing to say about the former.

This is largely because physics has little to say about brains.

stunney said...

This is largely because physics has little to say about brains

This is true. But brain science has a lot to say about brains. The micro-constituents of a brain are none of them brains. But we can explain what a brain is in terms of its nonbrain physical micro-constituents, just as we can explain what temperature is in terms of molecular kinetics.

So far, so good.

And this explains consciousness, how?

I still think the key argument is Kripke's. To wit, a sensation of heat is not essential to what heat is. But a sensation of pain is essential to what pain is. Take away a sensation of heat and there will still be heat. Take away the sensation of pain and you will have taken away pain.

The basic metaphysical point is this: one can in many contexts make a distinction between what something is--the real nature of a thing, and how it appears to us. But in the case of pain-states, or other states whose nature essentially involve consciousness, there just is no distinction to be drawn between the real nature of such states and how such states appear to us (or to other sentient creatures). In these cases, reality and appearance are one and the same thing.

To take Kripke's example, if one leaves out of a list of pain's essential, constitutive properties---the properties that go to make something actually BE pain---the phenomenal property of how pain FEELS, one would be leaving out the crucial, most essential property pain has. If some state S doesn't feel painful, S just is not a state of pain.

Another example is color and color-sensations. Blue light = electromagnetic radiation of a certain wavelength. But a state S is not a blue-sensation state if it lacks the phenomenal property of appearing-blue, because the reality of a blue-sensation state and how a blue-sensation appears to phenomenal consciousness are one and the same thing. Take away the blue-appearing, and you've taken away the blue-sensation itself. Yet light of the relevant wavelength could easily remain, filling a given space around a person's brain. (But the person is blind, or sleeping, or wearing goggles that prevent blue-sensations being triggered by the ambient blue light.)