What It's Like and Why: Subjective Qualia Explained as Objective Phenomena

Jeffrey Alexander Medina


Thomas Nagel, in 'What Is It Like To Be a Bat?', presents a conception of physical phenomena that limits reduction of its definition, at the very least, to objective phenomena.  He provides a number of arguments for rejecting the physicalist's theory of the world and mind, although none of them are particularly convincing, which I intend to show in what follows.  Contrary to Nagel's arguments from negativity, a consistent and exhaustive physicalism is readily conceivable, and I will develop one possible example of such a theory, with the arguments of Paul Churchland as my foundation.


     On Nagel's view, physicalism is the belief that everything that exists is completely objective.  His view leaves the possibility of further definition open, but vague.  This does not present a problem, however, considering that the objective nature of physical reality is the primary aspect under attack throughout his objection to physicalism.

     Nagel argues against physicalism by appealing to the phenomenological features of consciousness.  He claims that the experiences of conscious beings are subjective[1], and presents a nested argument to convince us of this.  We may refer to this as Nagel's second premise.  His first, outlined previously as a sort of minimalistic definition for physicalism, is that physical knowledge is necessarily objective knowledge.  If these two premises prove valid, it is a simple matter to conclude that consciousness cannot be consistent with physicalism, and this is precisely what Nagel does.  Since consciousness exists,[2] physicalism must be false.

     There is still the matter of Nagel's nested argument, the argument for his second premise.  He substantiates the claim that conscious experience is subjective by elucidating the obvious fact that the only being's conscious experience we are privy to is our own.  No physical theory to date allows me to know what it is like to be you, nor, in Nagel's example's context, to know what it is like to be a bat.  He allows that we might be able to imagine what experiences are like for other conscious objects, but with no objective assurance of whether we are right or not, our ignorance concerning 'what it is like' for others remains.  He also repeats in a number of ways, without providing much weight to his argument, that finding a physical theory consistent with this lack of knowledge is inconceivable, intractable, seemingly impossible, and so forth.


     Churchland, in 'Reduction, Qualia, and the Direct Introspection of Brain States,' finds Nagel is making three distinct arguments, each of them unequal to the task.  In the following, I present outlines of his objections, as well as my own assessments and corrolaries, as appropriate.

     The first of Nagel's arguments[3] discussed by Churchland suggests that the physical reduction of an ordinary substance excludes the phenomenal features of that substance.  Churchland sees this claim as plainly false, providing objective descriptions of three phenomenal features; the redness of an apple, the warmth of a coffee cup, and the pitch of a particular sound.  Up to this point, Nagel could still object that these descriptions leave out knowledge of what it is like for himself or a bull to see red.  He even commented to this effect concerning the reduction of sound to wave phenomena, claiming that such a reduction excludes the listener's point of view.  As Churchland continues, though, two qualifiers stand out that appear to quell this objection; (i) that the resolution at which our sensory mechanisms operate is less than perfect, and (ii) that the only subjective qualia of the redness of an apple or the dissonance of a sound is in our mind.  Implicit in the combination of (i) and (ii), though whether Churchland recognized this or not is unclear, is the idea that what redness is like for you must differ from what redness is like for me in a physicalist account of reality, given that our physical compositions are different and our senses are dependent on our physical bodies to operate, and that this is a potential physicalist account of the origin of our subjective perceptions.

     Extending Churchland's ideas, we find that the ways experience 'is like' for each of us vary and emerge do not necessarily preclude objective analysis, within a sufficiently advanced neuroscience.  The assertion that I cannot know what it is like to be you is not only not an indictment of physicalism at all - it is a logical extension of it - because what it is like for you to see red corresponds directly to the interaction between your physical apparati occupying a particular point in space and time and some random objective apple, while I, possessing a different physical composition and position in spacetime, can only experience my own unique phenomenon.[4]

     This realization impresses itself upon the second argument Churchland finds Nagel making as well; in fact, Nagel's second attempted argument against a physicalist reduction of the mind is wholly subsumed and predicted by the necessary extension of physicalism presented above.  Nagel's complaint, as reiterated by Churchland, is that the qualia of sensations are accessible through introspection, while brain states are not, and, alternately, that brain states can be viewed from a variety of perspectives, while qualia are knowable only to the subject.  This is as it should be; my account of physicalism requires, as explained above, that first-hand knowledge of sensational qualia is available only to the subject experiencing the sensation, while second-hand knowledge evades objective observation at the moment simply because we do not yet have significantly advanced technology to monitor the very intricate and personal physical chain reaction that occurs when you see an apple.

     Churchland advances a similar objection to the one he forwarded against the first argument.  He points out that Nagel is confusing the objective reality of a perceptible quality (or state, or phenomenon, etc.) with the objective reality of our perception of that quality.  Nagel is ascribing both data to the quality equally, even though the properties at hand are based on specific perceptions of the quality, and not really a property of the quality at all; that is, he is assigning properties to objective phenomena based on their being "kicked inwards to the minds of observers," as he was first accused in Churchland's rebuttal of his first argument.  Churchland's analog to temperature is an excellent one for clarifying what is wrong about Nagel's argument, and so I include it here,


"1.  Temperature is known by me, by tactile sensing, as a feature of material objects.

2.  Mean molecular kinetic energy is not known by me, by tactile sensing, as a feature of material objects.

[thus]  3.  Temperature is not equal to mean molecular kinetic energy,"


with the caveat that one keeps in mind the distinction between objective temperature and an individual's neurophysiologically objective perception of temperature, as described previously.

     This distinction in mind, it is impossible not to be able to objectively capture the perception of a thing.  Consider two rain clouds in a thunderstorm -- due to their respective compositions, they will predictably respond differerently to the electromagnetism and atmospheric chemistry with which they interact, and it is clear that if there is anything it is like to be one of those clouds, it is quite different from what it is like to be the other.  Additionally, the physicalist account predicts that one cloud cannot respond in the same way as the other (i.e., have an experience identical to the other's) without being transformed into a compositional replica of the other, yet one would be hard-pressed to support the accusation that the 'subjective' and unique reactions of clouds to their environments is anything but physical.

     The third argument Nagel makes is so similar to Frank Jackson's knowledge argument, on Churchland's view, that he decides to address it indirectly through Jackson's.  In Nagel's account, total physical knowledge of the bat's neurophysiology and interaction with the world leaves out what it is like to be a bat; in Jackson's, a neuroscientist named Mary, with total physical knowledge of the world (obtained in a black-and-white room), still does not know what it is like to see color.  In a general sense, the first premise is that one knows all there is to know about physical reality, the second, that one does not know all there is to know about sensations, and, the conclusion, that sensations are not physical in nature.

     Churchland says he finds two faults in these parallel arguments, with specific reference to Jackson's.  First, that the first and second premises make use of differing meanings of 'knows about.'  In the first premise, knowledge is presented as transferred and bounded by language, yet in the second, knowledge is represented in a very different medium, at some sub-linguistic level.  All that this means is that the brain has more methods of acquiring, storing, and handling information than the merely sentential.

     Though Churchland claims to be providing further support for his first objection to Jackson and Nagel, the criticism he puts forth next qualifies as a distinct objection in its own right.  The knowledge argument, if correct, simply proves too much.  If we alter the first premise of the knowledge argument such that instead of complete physical knowledge, Mary has gained complete non-physical knowledge (whatever substrata this involves), we find she will still not know what it is like to see color; thus, a dualist account of the mind is inadequate as well.

     The third (second, by his numbering) fault Churchland finds is in Jackson's implication that Mary could not imagine what seeing color would be like.  To the contrary, he finds that neuroscientific information alone could give Mary information about the qualia of seeing a color she had never seen before.  His exposition of how she might do this is quite detailed, but can be summarized in his analogy to the way musician's distinguish between chords and imagine new ones.  Chords, like colors, to the untrained typically seem to lack internal structure.  Those skilled in music, however, far below the level that Mary is skilled in the neuroscience of vision (since hers is a perfect knowledge and theirs is not), are able to produce the sound in their mind, by introspection alone, of a chord they've never heard or no longer remember.  If they can extrapolate in such a way, why can't Mary do so?

     To add to Churchland, not only does it seem plausible that the same can be done with colors, it is done with colors - by those talented and trained in art.  An artist with sufficient knowledge of color theory can conceive of any number of previously unseen colors.  Thus, it can be seen without much difficulty how Mary, with her propositional representation of neuroscientific knowledge, could imagine neurological states she has yet to experience for herself.


     Our inability to know what it is like to be a bat, or even simply another human, is not an indictment of physicalism, as Nagel suggests, but an epistemic limitation imposed by the fact that we cannot decouple the means of experience (i.e., sensory apparati) from the experiencer.  I can neither interact with, nor therefore experience, the environment precisely the way you do, any more than a pair of lakes can react in precisely the same way to rainfall or carbon dioxide pockets, yet they remain a clear example of an objective physical system -- and, in this way, so are we.




Paul Churchland, ‘Reduction, Qualia, and the Direct Introspection of Brain States’, Journal of Philosophy, January 82, no. 2, 1985.

Paul Churchland, Matter and Consciousness, MIT Press, 1984.

Frank Jackson, ‘Epiphenomenal Qualia’, Philosophical Quarterly, 32, 127, 127-136, 1982.

Frank Jackson, ‘What Mary didn’t know’, Journal of Philosophy, 83, 5, 291-295, 1986.

Thomas Nagel, The View from Nowhere, Oxford University Press, 1986.

Thomas Nagel, ‘What Is It Like to Be a Bat?’, Philosophical Review, 435-50, 1974




[1]   When referring to Nagel, unless otherwise specified, subjective should be taken to mean "incapable of being completely understood from an objective perspective or via objective analytic methodology (e.g. the physical sciences)," as opposed to merely seeming incapable of such analysis, and objective as "objective in totality; exhaustively reducible to the purely physical."

[2]   This may be seen as a third premise, and challenged as such, inasmuch as consciousness is considered to be a special quality of various living things, but just where we should draw the line in what we consider conscious remains an unresolved question.  Even requiring that being alive is a prerequisite (or perhaps co-requisite) of consciousness is not fully accepted, and even if it were, we would still have to resolve just what warrants being labeled 'life' or 'alive.'  It's a sort of catch-22, in that we must first define consciousness to accurately determine to which objects it applies, while the examples we use for our arguments concerning the nature of consciousness assume said determination (e.g. Nagel's proposal that we view bats as conscious, fish as iffy, amoebae and planets as not)

[3]   While Nagel makes no argument for this per se, he reveals that he assumes it to be true when he says,


            "It is impossible to exclude the phenomenological features of experience from a reduction, in the same way that one excludes the phenomenal features of an ordinary substance from a physical or chemical reduction of it - namely, by explaining them as effects on the minds of human observers."


[4]   The part of knowing I refer to here as unknowable in physicalism is knowing first-hand.  That is, I cannot feel the way you do in exactly the same way you do, short of possibly becoming you in some unforeseen way.  This is not to say, though, that I could not know what an experience was like for you, or what type of experience (painful, enjoyable, red-sighting) you were having, given knowledge of complete neuroscience and accurate knowledge of your brain states over the course of the experience.