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From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Subject: Re: Minsky's new article
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Date: Thu, 17 Nov 1994 23:14:34 GMT
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In article <CyyGMH.7sL@aisb.ed.ac.uk> Simon.Perkins@ed.ac.uk writes:
># It's an old argument, but for those who aren't familiar with it I'll
># give a brief example. I look at my screen right now, and there's a
># little yellow rectangle that represents the cursor. Now I know that
># yellow light has certain physical properties, and that it stimulates
># the visual receptors in my eyes in a certain way, and the receptors
># in turn send certain signals along the optic nerve to the visual
># cortex, etc.; but nowhere in that purely physical description of a
># sequence of events is there room for the *experience* of yellowness.
>
>I think this is entirely circular. You are happy to accept that
>looking at the yellow square on the screen causes a chain of
>neurological events to occur in the brain, but then you deny that this
>is the same as an `experience' of yellowness. In doing so you are
>boldly saying that the experience of yellowness CANNOT be a physical
>phenomenon. But this is what you are setting out to prove! Namely that
>consciousness (and things `perceived' by it) CANNOT be a physical
>phenomenon.

I'm sorry, but in the paragraph you quote, he does not use the
word "cannot".  So what's circular about the argument in that
paragraph?

I'll agree that it comes nowhere near proving its case.  "Nowhere
... is there room" is asserted, rather than shown.  What does this
"room" amount to?  It's rather unclear.

But it's also unclear where the experience of yellow will appear
in the physical account.  That in itself doesn't necessarily
support dualism, but it does suggest that there's still some
work to do before a convincing physical explanation is at hand.

>Here's an alternative argument based on the same situation (and
>equally circular, but one that I happen to belive for other reasons -
>see below):
>
>From a mechanistic point of view (such as my own), the brain is a
>(very complex) machine. Things like consciousness and intelligence are
>dynamic `properties' or descriptions of the working machine.
>Perceptual events such as the yellow square cited above trigger
>changes in the working of this machine (I assume you have no problem
>with this). And since `consciousness' is `merely' a description of the
>machine, then the consciousness is also changed. Translating this
>event into English, we say that we've experienced the yellow square.

What do you mean by saying consciousness is a description of the
machine?  How does an experience of yellow result?

>I realise that the last paragraph contains some tough pills to swallow
>for some people. After all we all `know' that we have the free will to
>choose our behaviour, don't we? However, research in neurobiology in
>animals has continually found that animal behaviour that at one level
>is frequently explained in terms of `intentions' or 'desires', can
>also be explained in terms of mechanistic neural ciruitry.

But there are at least two ways to understand that.  On is that the
explanation in terms of intentions and desires was false.  Animals
don't have intentions and desires; they're purely mechanical.

>For me, it is this (admittedly small, but growing rapidly) body of
>neurological evidence, suggesting that behaviour is controlled by
>mechanistic processes, that sets the mechanistic view apart from pure
>`religion'. (But I'm prepared to admit - not that far...)

Are those the only possibilities?  Mechanism or religion?

>There are of course many other arguments against dualism but I think
>I'll stop right there...

BTW, have you seen David Chalmer's arguments for "property dualism"?
His thesis and various articles are on-line.

-- jeff

