From: Harnad, Stevan (harnad@cogsci.soton.ac.uk)
Date: Mon Oct 23 1995 - 18:37:34 BST

Hi Cog-Founders:

Here's a quick overview of the last session. I say quick, because
the comments on Lubinsky & Thompson are already coming in, so there
will be little time to cover retrospective ground!

We talked about the "cerebroscope," the psychologist's dream: an
instrument, like a thermometer, that measures mental states. It
correctly registers when you are seeing blue (or feeling "blue"),
in both quantity and quality...

Quantity AND quality? How could it measure the QUALITY of your
experience? It could produce an analog signal that correlates exactly
with each dimension of your experience, but that's still just quantity,
not quality. If someone didn't already know what the experience of blue
felt like, then reading the cerebrescope's metres would not tell them;
the scope would simply correctly match what the subject was feeling
with a quantity that can be TRANSLATED into a description of the
experience (for anyone who already knows what the experience is).

Kate told us about the way she described colors to a blind friend: Red
is like hot and blue is like cold. But if someone had never seen red or
blue, would they really get anything from that analogy (other than that
there are sensations, heaven knows which, that are like hot and cold, but
they are not actually hot or cold...)?

Besides, the "cerebroscope" has an even worse handicap, because it must
"code" experiences without the help of any other experience, even as an
analogy: it's all quantity, and no quality, though it correlates with
and predicts quality perfectly.

I mentioned Nagel's paper on "What Is It Like To Be a Bat?" to suggest
that there is no one who can tell you what it's like to have a sense
that you don't have (sonar): They can only suggest that it might be
SIMILAR to this or that sense you already do have, but it should be
obvious, as with blue and cold, that the analogy with temperature does
not really convey the quality of color: It just says there's something
about color that resembles temperature. But we already know what
temperature is like: What is color like (if one is blind) or what is
sonar like (if one is human)?

If you understand the problem of translating experience in one
sense to experience in another (it is not possible), then consider
how much worse the problem of translating experience into something
OTHER than experience has to be. The cerebroscope would clearly not help
you know the sonar experiences of a bat: It would just allow you to
predict perfectly the bat's behaviour in response to sonar signals.
In OUR case the measurements of the cerebroscope could be translated
into the LANGUAGE with which we describe experience -- but clearly that
language would only make sense to someone who HAD those experiences.

Is it different with any other "scope"? Consider a stethoscope -- an
automatic one, not relying on the doctor's ear to hear the heartbeat,
but registering it as blips on an oscilloscope screen. You might be
tempted to say the problem's the same there, because a blip on a scope
screen and a heartbeat are not the same thing. But besides the scope
measurements, you can also get all the anatomical and physiological and
pharmacological facts about the heart, and eventually that would
include everything there is to be known about a heart. Nothing would be
left out. There's no more to a "heartbeat" than that.

Not so with the cerebroscope (whose official organ, is, after all, the
brain). For even if you got all the anatomical, physiological and
pharmacological facts about the brain, that still wouldn't tell you
what the scope was really measuring, namely, experience. You'd just
have to take that on faith.

Now Richard suggested that that may just be because we just don't know
enough yet. He suggested that there are examples from other areas of
science where more knowledge made what had looked like an insoluble
problem or a mystery vanish. We discussed how, for example, heat, which
had been thought to be an independent property of matter, like
electricity or gravity, turned out to be average molecular motion
instead. Similarly, life turned out to be certain biochemical
properties. In both cases, there was -- in the face the new explanation
of what heat and life were: molecular motion and biochemical properties
-- no left-over question about how the one could really be the other:
there was no heat/matter or life/matter problem, analogous to the
mind/matter problem.

So Richard thought it seemed reasonable to expect the mind/matter
problem to vanish too, without a trace, once we know more about just
what properties of matter mind really corresponds to.

The trouble is that there is some reason to believe that the case of
mind is rather different from cases like heat and life, and the difference
suggests that Richard's extrapolation may not hold.

Note that every time we found out what something REALLY was (heat was
REALLY just mean molecular motion, life was REALLY just biochemistry),
a kind of a translation took place: What APPEARED to be this, turned out
to be that. But can that same translation process work when it is
appearances themselves that we are supposed to see as REALLY something
other than appearances? It's as if in all the other scientific cases, we
just traded appearances for appearances, when we successfully saw THIS
as really THAT. Can this work when we are trying to trade appearances
for something other than appearances?

This is just one little hint that the mind/matter problem may not be as
easily solved as the heat/matter problem or the life/matter problem,
which really are and always were nonproblems. We will encounter more,
but that's enough for now...


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