Replacing neurons with chips (was: Re: The copy paradox)

Damien Broderick (
Tue, 25 Nov 1997 21:56:43 +0000

At 05:53 PM 11/24/97 -0700, Brent Allsop wrote:

>>Once you replace the real phenomenal red with abstractly
>>represented red, the subjective experience is gone. You would
>>recognize this as soon as the first part of the visual cortex switched
>>to be abstract since it would then be a blind spot in your conscious
>>visual awareness.

At 09:22 PM 11/24/97 -0800, James Rogers commented:

>You are making a tight connection between the
>hardware and consciousness. There is nothing special about a neuron that
>synthetic duplicate couldn't contain. To say so appears to attach a
>mystical (and mythical) value to the individual neuron. [...]
>There is nothing intrinsically phenomenal about how the visual cortex
>processes the color red. The fundamental experience of red is only
>relevant to your consciousness in how it relates to the other parts of the

What Brent is talking about is allegorised by David Chalmers in his Fading
Qualia model (which, as I recall, that metaphysical dualist rather
surprisingly declines to accept). As the neural structures with their
supposed specific Searlean `causal powers' are chipped, something like the
neuropathology of Blindsight would be experienced. You'd find yourself
mysteriously functioning quite competently while your dumbfounded and
`blindspotted' consciousness assessed that you ought to be acting at
random. But this phenomenal glitch *already occurs*, to people without a
single implanted neurode. Brent's opinion is an act of faith (as, of
course, is James's and mine to the contrary), and I guess we'll have to
wait for some GregEganist experiment to learn which turns out to be the
case. But I judge that James's position is more firmly consistent with
everything else we already know about the material world. Surely Brent
would allow a single atom to be replaced, or a single molecule (since,
after all, this is always happening). At what exact point of replacement
would the allegedly unique powers kick in? Even when one grants the
extraordinary and difficult special character of experience - of qualia, of
phenomena, of what mind's functioning *is like* from the inside - I can't
see any reason at all to expect it to require any more mysterious material
explanation than hypercomplex relatedness, which we know describes the
brain and which can be replicated piecemeal (in principle at least) at
whatever degree of granularity.

Damien Broderick