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See Pylyshyn s recent target article in BBS, (April 2002) and my commentary,  Does your brain
use the images in it, and if so, how?
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 Philosophers should not find themselves having to abandon pet theories about the nature
of consciousness in the face of scientific evidence. They should have no pet theories, since they
should not be propounding empirical theories that are subject to empirical confirmation and
disconfirmation in the first place. Their business is with concepts, not with empirical judgments; it
is with the forms of thought, not with its content; it is with what is logically possible, not with what
is empirically actual; with what does and does not make sense, not with what is and what is not
true. (p404). It is this blinkered vision of the philosopher s proper business that permits Hacker
to miss the mark so egregiously when he sets out to criticize the scientists.
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not discover anything. Marr was not an idiot. He understood that. Now, what about Marr s theory
of the sub-personal processes of vision?
Moreover, it is altogether obscure [emphasis added] how the mind s having access to
putative neural descriptions will enable the person to see. And if Marr were to insist
(rightly) that it is the person, not the mind, that sees, how is the transition from the presence
of an encoded 3-D model description in the brain to the experience of seeing what is before
one s eyes to be explained? To be sure, that is not an empirical problem, to be solved by
further investigations. It is the product of a conceptual confusion, and what it needs is
disentangling. (p147)
I would have said, on the contrary, that it is a philosophical problem to be solved by addressing
those who find it  altogether obscure and leading them to an understanding of just how Marr s
theory can account for the family of competences that a seer has.22 Marr was more or less taking it
for granted that his readers could work out for themselves how a model of the brain as having a
consultable 3-D model of the world would be well on the way to explaining how a creature with
just such a brain could see, but if this eluded some readers, a philosopher would probably be a
good specialist to explain the point. Just asserting that Marr is suffering from a conceptual
confusion has, as Russell so aptly put it, all the advantages of theft over honest toil.
. . . For seeing something is the exercise of a power, a use of the visual faculty not
[emphasis added] the processing of information in the semantic sense or the production of
a description in the brain. (p147)
This  not is another theft. What has to be explained is the power of the  visual faculty and that
power is explained in terms of the lesser powers of its parts, whose activities include the creation
and consultation of descriptions (of sorts). These examples could be multiplied to the point of
tedium:
It makes no sense, save as a misleading figure of speech, to say, as LeDoux does, that it is
 possible for your brain to know that something is good or bad before it knows exactly
what it is. (p152)
But who is misled? Not LeDoux, and not LeDoux s readers, if they read carefully, for they can see
that he has actually found a very good way to make the surprising point that a specialist circuit in
the brain can discriminate something as dangerous, say, or as desirable, on the basis of a swift sort
of triage that is accomplished before the information is passed on to those networks that complete
22
For an example of such a type of explanation, see my simplified explanation of how
Shakey the robot tells the boxes from the pyramids (a  personal level talent in a robot) by (sub-
personally) making line drawings of its retinal images and then using its line semantics program to
identify the tell-tale features of boxes, in Consciousness Explained.
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the identification of the stimulus. (Yes, yes, I know. Only a person a doctor or a nurse or such
can perform the behavior we call triage; I am speaking  metonymically . Get used to it.)
In conclusion, what I am telling my colleagues in the neurosciences is that there is no case
to answer here. The authors claim that just about everybody in cognitive neuroscience is
committing a rather simple conceptual howler. I say dismiss all the charges until the authors come
through with some details worth considering. Do the authors offer anything else that might be of
value to the neurosciences? They offer no positive theories or models or suggestions about how
such theories or models might be constructed, of course, since that would be not the province of
philosophy. Their  correct accounts of commissurotomy and blindsight for instance consist in
bland restatements of the presenting phenomena, not explanations at all. They are right so far as
they go: that s how these remarkable phenomena appear. Now, how are we to explain them?
Explanation has to stop somewhere, as Wittgenstein said, but not here. Bennett and Hacker quote
with dismay some of the rudely dismissive remarks about philosophy by Glynn, Crick, Edelman,
Zeki and others (pp396-98). On the strength of this showing, one can see why the neuroscientists
are so unimpressed.23
23
Bennett and Hacker s Appendix 1: Daniel Dennett does not deserve a detailed reply,
given its frequent misreadings of passages quoted out of context and its apparently willful
omission of any discussion of the passages where I specifically defend against the misreadings
they trot out, as already noted. I cannot resist noting, however, that they fall for the creationist
canard that they presume will forestall any explanations of biological features in terms of what I
call the design stance:  Evolution has not designed anything Darwin s achievement was to
displace explanation in terms of design by evolutionary explanations. (p425) They apparently do
not understand how evolutionary explanation works.
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