From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Dualism
Organization: Indiana University
Date: Wed, 30 Sep 1992 06:40:38 GMT

In article <1992Sep28.203519.133337@Cookie.secapl.com> frank@Cookie.secapl.com (Frank Adams) writes:
>In article <Bv9vGp.Ax3@usenet.ucs.indiana.edu> chalmers@bronze.ucs.indiana.edu (David Chalmers) writes:

>>explanation here won't do.  There is also the secondary question
>>of why it feels like *that* rather than like *this* -- it seems
>>perfectly coherent that our blue experiences and red experiences
>>could be systematically inverted, for instance.
>
>Do you think how it feels has no behavioral consequences?  Would you behave
>as you do if your blue experiences and your pain experiences were
>systematically inverted?

If this inversion could be performed without affecting my physical
structure, then yes.  Now in this case (the blue/pain inversion),
I suppose the inversion is logically possible, as disembodied
blue and disembodied pain seem logically possible, and zombie me
seems logically possible, so just combine the two the wrong way
around, so to speak.  However, do to so would violate what I've
called the coherence between our psychological states and our
phenomenal (conscious) states, as the structure of the phenomenal
states here (e.g. pain) wouldn't be remotely parallel to the implicit
structure of the psychological state (e.g. the judgments the system
makes about blueness), so such a creature would be bizarre indeed.

It's much more reasonable to imagine a blue/red inversion, because
in this case it seems that this inversion could be made without
violating this coherence, and the relation between the phenomenal
and the psychological wouldn't seem all that different from normal.
Of course, the blue experiences would now be labeled "red", and
associated with blood and the like.  But apart from that sort
of thing, there doesn't seem to be any vast difference between
the functional role of blueness and that of redness that would
make this kind of inversion bizarre.  Joseph O'Rourke suggested
that blue is "darker" than red, so that in this case a darker
experience would be accompanied by the judgment that the experience
is lighter -- which would be a degree of decoherence -- but
this doesn't seem to be the case to me.  There are darker and lighter
shades of both blue and red; we just have to make sure that in
the inversion, we map shades of the same darkness onto each other.

This is of course a subtle matter, and it may well be the case
that there are subtle asymmetries in colour space that would
mean any inversion would have to involve some amount of decoherence
of the intrinsic properties of qualia from the judgments we made
about them (if not brightness, then maybe warmness and coldness,
or positivity and negativity).  This is controversial, but in any
case we can get around those problems by talking about inversion
in beings who have a symmetrical colour space (whether or not we
do).

There are a few fascinating articles on this, relating the possibility
of spectrum inversion to the symmetries or otherwise of colour space.
The key reference is Hardin's _Color for Philosophers_, which is a
terrific book.  Since then there has been an extended debate between
Hardin and Joe Levine, as follows (annotations from my bibliography
on the philosophy of mind):

Levine, J. 1983.  Materialism and qualia: The explanatory gap.  Pacific
Philosophical Quarterly 64:354-61.
  How do we explain the apparent contingency of the qualia-matter reduction?
  Even if it's not metaphysically contingent, it's conceptually contingent, so
  there's a gap in any physical explanation of qualia.  Excellent.

Hardin, C.L. 1987.  Qualia and materialism: Closing the explanatory gap.
Philosophy and Phenomenological Research 48:281-98.
  On the physiological bases of phenomenal states, particularly color.
  Inverted spectrum isn't really coherent, as coolness/warmth would have to
  be inverted too.  So the contingency of qualia is diminished.

Levine, J. 1991.  Cool red.  Philosophical Psychology 4:27-40.
  Contra Hardin 1988: there's a "green residue" after coolness is subtracted,
  so inverted spectrum could still be possible.  In any case, the impossibility
  of IS doesn't affect the explanatory gap for qualia, which is epistemic.

Hardin, C.L. 1991.  Reply to Levine.  Philosophical Psychology 4:41-50.
  Reply to Levine 1991.  "Green residue" and "red residue" may be identical.
  Physiology might put more constraints on qualia, eventually ruling out all
  other possibilities.  But there may still be absent/alien qualia problems.

-- 
Dave Chalmers                            (dave@cogsci.indiana.edu)      
Center for Research on Concepts and Cognition, Indiana University.
"It is not the least charm of a theory that it is refutable."