To this it has been objected, notably by Block (1990, 1995, 1998) that we are aware of some specifically mental property when we perceive objects.  Perceptual experiences have, according to Block, qualities that we are aware of which go beyond their representational properties, and they are the phenomenal qualities.  To see red, he argues, is not just to be aware that there is a red thing in front of one’s eyes—it is also to be aware of ‘what it’s like’ to see the red thing.  Block’s use of the inverted spectrum and ‘inverted Earth’ thought experiments are designed to show that representational content could conceivably vary independently of ‘phenomenal feel’.  Block (1996) has famously described the gap between pro- and anti-intentionalists as “the greatest chasm in philosophy of mind—maybe even all of philosophy.” An important aim of this paper is to attempt to bridge this ‘chasm’.

My approach here is to argue for this conditional, rather than for the conditional together with the thesis that dispositionalism about colour is correct. For this reason dispositionalism is largely, though not entirely, taken for granted. Moreover I leave aside the issue of versions of dispositionalism—for example, whether colours are to be identified with dispositions or with the categorical basis of dispositions—since, as far as I can tell, nothing here turns on which of these version are correct.  Readers unsympathetic to dispositionalism about colour may find that the position put forward here inherits what is problematic about that view. But it will be enough if the position I propose is as plausible as dispositionalism about colour. I leave it open whether an alternative view of colour could be adapted to suit qualia in the way that I adapt dispositionalism about colour; there is no reason on the surface to suppose that it could not.

A little later he writes that “in the case of mental phenomena there is no ‘appearance’ beyond the mental phenomena itself.” (p. 154)  But his main reason for asserting this thesis is that we pick out sensations by the way they feel and that, for example, “if any phenomenon is picked out in exactly the same way we pick out pain, then that phenomenon is pain.” (p. 155)  And this is precisely the semantic thesis which as we have just noted fails to entail the ontological thesis.6  All that is required for the semantic thesis to hold is that a state be pain just in case it is the kind of state that normally feels painful.  The ‘normally’ caveat allows for the possibility that pain and the feeling of pain might not always co-occur—as for example, when one has a continuous mild headache but does not continuously feel it.  At the same time to understand “pain” one must understand that pain is nothing more than a state that, as we might say, typically presents a painful appearance—that typically feels painful.  In this way we arrive at a dispositional account of phenomenal qualities along the same lines as the dispositional account of colour and other ‘secondary’ qualities:

  In order to carry beyond analogy the idea that the way sensations feel is the way they appear, a case must be made that they appear to someone.  The inner sense theory supplies this, for in this theory perceptual states can literally be perceived.  And if they are perceived then ipso facto they must have appearances.  Moreover those appearances are in an important sense the direct result of the inner sense, in the same way that colour appearances (as distinct from colours) are the result of colour perception.  The inner sense itself would not, if this approach is right, have its own phenomenal quality because it does not have an appearance.  It does not have an appearance because its states are never themselves perceived.7  So for any sensation there is only one phenomenal quality associated with it.  There are two kinds of appearance involved, but one of them is of objects in the external world (their colour, shape, etc.) and the other is of sensations (their feel).

According the current proposal, in being related essentially to a disposition, phenomenal qualities are analogous to solubility, for which an explanatory gap exists in the following way.  A bare description of the molecular structure of salt is not an explanation for why salt is soluble.  What needs to be added is what would happen to that structure if it were surrounded by H2O molecules.  And that could not be explained without describing, at least partially, the structure of those H2O molecules.  The “gap” in this case is not of course a real explanatory gap in the sense that there is some aspect of the solubility of salt that cannot be explained.  But it a gap in the sense that no amount of information about salt alone could explain why salt is soluble.  Anyone hoping to find an explanation for the solubility of salt entirely within the chemical nature of NaCl molecules would find themselves up against a real gap.  Furthermore it would be a gap, I claim, of precisely the kind operating in the case of phenomenal qualities.

To see this, take firstly the case of the (primary) perception of an object with a red appearance.  Now no amount of information about the surface properties of the rose could explain the fact that it has a red appearance without it being taken as given that those properties cause perceptions of red in us and that the light is normal.  That is because whatever properties the rose has, a change in the ambient light could change its appearance (which is not of course to say that its colour would thereby change, merely its colour appearance). The rose considered in isolation is not wholly responsible for its having a certain colour appearance, so even after a complete physical description of it is given it remains an open question what colour it will appear to be.  To close the question it needs to be added that rose and the conditions are such that it will be perceived as red.

We can now tell a similar story about perceptions themselves.  If we are interested in explaining why our perceptions feel the way they do, then our explanandum is not their nature but rather their appearance.  But the way it appears is not something that a perceptual process considered in isolation could be wholly responsible for.  The “could” here, as in the case of colour appearance, is the logical could.  Since an appearance is a relational property,9 the fact that it holds of an object or process must be made true partly by something else.  Hence, as long as our attention is focussed exclusively on the perceptual process itself we could not possibly explain why it feels the way it does.10  In order to explain that we also need to take into account the way in which we are perceiving that process.11

As it happens, Wolf Singer (1998, 2001), a neurophysiologist, has recently been speculating that one of the roles of the now-familiar 40-Hz synchronous firing of neurons in parts of the cortex may be to represent perceptual processes.  He goes so far as to propose that “the aspect of consciousness that we address as phenomenal awareness results from an iteration of the same cognitive operations that support sensory processing.” (p. 127)

Crick and Koch’s (1990) original paper on the firing of certain neurons in unison proposed that it is involved in perceptual binding, which they in turn proposed may be necessary for consciousness.  More recently, Crick and Koch (1998) have downplayed the role of synchronous firing, but Singer and his lab have taken it up as a vehicle of representation.13  Whether Singer is right that synchronous firings are, in particular, the vehicle of an iterated, perceptual representation is another matter.  But at any rate Singer’s papers show that there is some reason to at least keep the empirical question open for now.  That is the most that my proposal here needs.

The red appearance of a rose in normal light is explained partly by the fact that in normal light we perceive it to be red.  We represent it, somehow, as being red.  But in doing so, what do we know about the rose?  Locke argued that a key feature of our ideas of secondary qualities is that they lack any resemblance to a discoverable feature of objects—“There is nothing like our ideas [of secondary qualities] existing in the bodies themselves” (II;VIII;15).  One plausible interpretation of this is that our sensations of colour don’t seem to tell us anything about the natures of the objects we see to be coloured.  Now of course this itself can not serve as an argument to the conclusion that colour perception is not a perception of a real property of objects.  Even Locke’s characterisation of secondary qualities allows that they convey some information about their bearer, namely, the power to induce in us certain sensations.  Two red objects, by virtue of being red, have the same power with respect to inducing colour sensations.  Since it is possible to perceive some similarity without perceiving the features that account for it, there is no philosophical problem in the idea that in colour perception we represent sameness and difference without representing sameness or difference in any particular respect.

Like the perception of colour, our perception of what colour sensations feel like does not seem to reveal much about the nature of sensation states.  It does tell us at least this much, that the sensation of colour is a visual rather than an auditory sensation.  I will not speculate here on the usefulness of that kind of information but I do want to point out that there is no reason to think that phenomenal qualities are not inner sensings simply because they do not reveal anything of the nature of visual processing.14  Colour perception is a good example here—to perceive that two objects are the same colour is not really to know what properties they share, if any, apart from simply their colour.  Likewise, to notice that the perception of red and the perception of orange feel similar is not to know what properties they have in common.  Their feeling similar just is one’s perception that they are similar.  We cannot articulate the respects in which they are similar because it isn’t part of the intentional object of the perception, and it needn’t be in order to count as one.  

If the approach outlined here is on the right track, it is clear that a theory of representation is needed by the study of phenomenal qualities.  Within the framework provided here, which is consistent with the hard-line representationalism of Harman, the views, or anyway the intuitions, of most anti-representationalists can be accommodated.  Our awareness of the quality of our sensory experience does not threaten the idea that perceptions are representational, since that awareness is itself representational.  What it represents is to some extent unimportant, and may only be bare similarities and differences.  Like all perceptual systems, they represent the world in a way that is evolutionarily useful, which does not necessarily cut nature at its joints—a quality we expect rather of our scientific representations.

In the light of this it may be useful to take a somewhat novel approach to the so-called “knowledge argument” against physicalism, which has not yet been addressed here.  In Jackson’s (1982, 1986) argument Mary has full knowledge of an ideal neuroscience but has never seen colours, to which the question is put, does Mary learn anything on having her first visual colour experience?

As a first pass across this question, it is worth asking whether if Mary were a physicist she would learn anything about red objects on first seeing something red.  In one sense she would, since she would learn what red objects look like.  But—a by now familiar point—the way objects appear is not given purely by any characterisation of the objects themselves.  How the objects are perceived is also an essential part of the story.  Nevertheless the red appearance of post-boxes, whether or not is a question answerable within physics, is a contingent fact for which we can seek an explanation.  The part that cannot be answered by Mary the physicist must presumably be answered by Mary the neuroscientist.  Still the question remains a question about post-boxes rather than mental states—did Mary the neuroscientist learn anything about red things on her first red experience?  Certainly her neuroscience should have told her how red things are perceived, and in that sense how red things appear.  If ideal neuroscience includes a representational theory of perception then Mary ought to have known what properties she would perceive the red objects to have—that is, redness.  That a certain class of objects would appear red ought not to have surprised her.