The subjective features of conscious mental processes--as opposed to their physical causes and effects--cannot be captured by the purified form of thought suitable for dealing with the physical world that underlies appearances." (Nagel, in Dennett, 1991, p. 372).

Once upon a time, there were two large black boxes, A and B, connected by a long insulated copper wire. On box A there were two buttons, marked *a* and *b*, and on box B there were three lights, red, green, and amber. Scientists studying the behavior of the boxes had observed that whenever you pushed the *a* button on box A, the red light flashed briefly on box B, and whenever you pushed the *b* button on box A, the (...) green light flashed briefly. The amber light never seemed to flash. They performed a few billion trials, under a very wide variety of conditions, and found no exceptions. There seemed to them to be a causal regularity, which they conveniently summarized thus. (shrink)

A family of compelling intuitions work to keep "the problem of consciousness" systematically insoluble, and David Rosenthal, in a series of papers including the one under discussion, has been resolutely driving these intuitions apart, exposing them individually to the light, and proposing alternatives. In this instance the intuition that has seemed sacrosanct, but falls to his analysis, is the intuition that "sensory quality" and consciousness are necessarily united: that, for instance, there could not be unconscious pains, or unconscious subjective shades (...) of blue, or unconscious aromas of freshly roasted coffee beans. The particular airborne polymers that are the vehicles of freshly roasted coffee beans could exist, of course, in the absence of any observer, and hence of any consciousness, but the sensory quality of that aroma requires--according to well-entrenched intuition--not only an observer but a conscious observer. Such properties have no esse except as percipi. (shrink)

"Qualia" is an unfamiliar term for something that could not be more familiar to each of us: the ways things seem to us. As is so often the case with philosophical jargon, it is easier to give examples than to give a definition of the term. Look at a glass of milk at sunset; the way it looks to you--the particular, personal, subjective visual quality of the glass of milk is the quale of your visual experience at the moment. The (...) way the milk tastes to you then is another, gustatory quale, and how it sounds to you as you swallow is an auditory quale; These various "properties of conscious experience" are prime examples of qualia. Nothing, it seems, could you know more intimately than your own qualia; let the entire universe be some vast illusion, some mere figment of Descartes' evil demon, and yet what the figment is made of (for you) will be the qualia of your hallucinatory experiences. Descartes claimed to doubt everything that could be doubted, but he never doubted that his conscious experiences had qualia, the properties by which he knew or apprehended them. (shrink)

Can the physicalist consistently hold that representational content is all there is to sensory experience and yet that two perceivers could have inverted phenomenal spectra? Yes, if he holds that the phenomenal properties the inverts experience are dummy properties, not instantiated in the physical objects being perceived nor in the perceivers.

Max Bennett is a distinguished Australian neuroscientist, Peter Hacker an Oxford philosopher and leading authority on Wittgenstein. A book resulting from their collaboration, Philosophical Foundations of Neuroscience, has received high praise. According to the Blackwell website, G.H. von Wright asserts that it 'will certainly, for a long time to come, be the most important contribution to the mind-body problem that there is'; and Sir Anthony Kenny says it 'shows that the claims made on behalf of cognitive science are ill-founded'. M.R. (...) Bennett & P.M.S. Hacker, Philosophical Foundations of Neuroscience (Oxford: Blackwell, 2003). (shrink)

In view of the excellent arguments that have been put forth recently in favour of qualia, internal sensory presentations, it would strike an impartial observer - one could imagine a future historian of philosophy - as extremely odd why so many philosophers who are opposed to qualia, that is, sensory experiences internal to the brain, have largely ignored those arguments in their own. There has been a fashionable assumption that any theory of perception which espouses qualia has long since been (...) overcome by a number of 'formidable' objections, in particular, the Homunculus/Infinite Regress Objection, the Solipsism Objection, Austin's Illusion/Delusion Objection, the Ludicrousness-of-Colours-in-the-Brain Objection, the Indirect-Realist-has-to-assume-Direct-Realism Objection, the Impossibility-of-Comparing-Internal-with-External Objection, the Impossibility of Intrinsic Experience, and several more minor varieties of these. It is uncanny how they continue to be repeated, indeed, with a kind of automatism, evidenced by the fact that none of those who repeat them appear to have taken note of the answers to the objections. Indeed, they only appear to refer to those philosophers with whom they agree: it has long been insisted upon in the study of rhetoric that one of the weakest things to do in an argument is to ignore the main points made by one's opponent:

[it is] the wisest plan _to state Objections in their full force_ ; at least, wherever there does exist a satisfactory
answer to them; otherwise, those who hear them stated more strongly than by the uncandid advocate who
had undertaken to repel them, will naturally enough conclude that they are unanswerable. It is but a
momentary and ineffective triumph that can be obtained by man. (shrink)