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Nagel on The Problem of Consciousness

(Excerpt from a paper I wrote a few months ago explaining the problem of consciousness.)

In his article “What Is It Like to Be a Bat?” Thomas Nagel argues that it is consciousness that makes the mind-body problem so problematic. It is his position that no psychophysical reductionist theory yet proposed has been successful in explaining consciousness. His claim is even stronger, however. We do not only have yet to construct a theory that successfully explains consciousness but we have yet to give an account of what a successful theory would even look like. According to Nagel, the very nature of consciousness itself may rule out the possibility of constructing a physicalist account of it.[1] If so, then it would seem to follow that any physicalist account of the world would forever remain incomplete.

According to Nagel, an organism is conscious “if and only if there is something that it is like to be that organism—something it is like for the organism.”[2] In other words, for an organism to be conscious it must have subjective experiences or a subjective character or nature. Lower life forms (like moths) and robots are often said to be without consciousness because while they may have many functional similarities with conscious organisms, they are internally or experientially empty.[3] There is nothing that it is like to be such entities (some philosophers refer to such entities as zombies). However, higher life forms such as humans, tigers, whales, and bats (essentially all mammals) are usually considered conscious because there is something that it is like to be them: they have certain sensory apparatuses and other cognitive functions that give rise to certain subjective experiences. And different organisms will, no doubt, have different types of experiences based on their difference in physical and neurological makeup; but all such organism are nonetheless conscious.

For Nagel, the problem of consciousness first arises for the physicalist when one considers that consciousness does not seem to be the sort of thing that can be cashed out in physical terms. If one were to observe the activities of another organism’s brain and describe the physical events that were taking place, one would not come to conceive of what it is like to be that organism. Even if one had access to a sophisticated machine that had the capability of mapping every physical property of the brain and every physical interaction going on inside of it, one would not thereby come to have a conception of what it was like to have the sort of experiences that the organism in question is having.

Here is an example to get this point across. Suppose that a Martian or some sort of intellectual alien life form incapable of perceiving the color red were to travel to earth and begin studying our brains. They go about studying the physical makeup of our brains, how neurons interact within our brains, and so on. The problem is this: merely observing all of the physical processes within our brains would not seem to give them a conception of what it is like to be appeared to redly. For where within the brain—in what neuron we might ask—is there the color red? Only being appeared to redly would seem to give one a conception of what it is like to be appeared to redly. If one is the sort of organism that is incapable of experiencing the color red, no amount of physical investigation of an organism’s brain will give one the conception of red. This is analogous to the case of the bat and its sonar apparatus: because we humans are not the sort of organisms that experience the world through sonar, no amount of physical investigation of a bats physical or neurological makeup will give us a conception of what it is like to be appeared to sonar-ly. We might be able to devise conceptual representations of what it is like to perceive the world through sonar, but such in only our representation. That would merely be what it is like for a human to perceive the world through sonar and not what it is like for the bat to do so. It would seem to be the case then that a completely objective, physical description of an organism’s brain—or of the entire universe for that matter—is always going to leave out the subjective element, namely, consciousness.

Note that the problem is not simply that of gaining access into another organism’s consciousness by analyzing their physical states. It is not merely the problem of being able to look at an organism’s brain while remaining ignorant as to what colors it is experiencing. This may be a problem. But for Nagel, the problem of consciousness is even more fundamental. The problem is not merely epistemological but conceptual. Thus, even if we were to suppose that our brains turned the color(s) that we were experiencing, this would not help the Martians experience red. Any red color on our brain would appear to them as something not red. They are fundamentally incapable of experiencing red and therefore fundamentally incapable of conceiving of it.[4] As far as bats are concerned, because I have such difficulty conceiving of what it would be like to be appeared to sonar-ly, I do not even know what it would look like for their brain to reveal what that was like. Even if studying their brains did give us some conception of what it was like to see the world through sonar, again, that would only be what it was like for us to see the world through sonar and not what it is like for the bat.

The fundamental problem of consciousness then is this: psychophysical reductionist theories, by their very nature, describe the world in objective, physical terms while consciousness, by its very nature, seems to be something subjective, non-physical, and irreduciblely so. In other words, reductionist theories are meant to eliminate dependence on any one particular point-of-view while consciousness relies on being a particular point-of-view. Nagel puts it this way,

If the subjective character of experience is fully comprehensible only from one point of view, then any shift to greater objectivity—that is, less attachment to a specific viewpoint—does not take us nearer to the real nature of the phenomenon: it takes us farter away from it.[5]

To put it a different way, suppose there are two distinct species that both describe a physical event in the same objective terms: suppose they both describe sound as a wave. There is nothing that says that because they both conceive of sound in the same objective manner that they both have the same subjective experience of it. One may experience sound like we do while the other experiences sound as colors or as something altogether inconceivable to us. But if we hope for our psychophysical reductionist theory to be successful, we must necessarily eliminate both of the species-specific viewpoints in favor of the objective viewpoint. It seems to necessarily follow then that any objective account of consciousness leads to its elimination simply in virtue of what an objective account is (less attachment to specific viewpoints). In essence, Nagel does not even understand what it would mean to give an objective account of consciousness. This is ultimately why Nagel is so skeptical about such reductionist theories succeeding.

[1] I say “may” only because Nagel remains open to the possibility of such an account one day being realized. But even if that day comes, it “lies in the distance intellectual future.” Thomas Nagel, “What Is It Like to Be a Bat?” Philosophical Review 83 (1974): 436.

[2] Ibid.

[3] Determining which entities are conscious and which ones are not is a problem unto its own. As Nagel asks: what sort of evidence would even count toward a thing being conscious? Strictly speaking, every organism including other humans outside of oneself could lack consciousness and one would not know it. For the current discussion, however, we can assume that there are many conscious beings.

[4] It is an interesting question whether or not one can conceive of a color one cannot perceive. It may be possible by making slight gradual variations to the colors one can perceive. But for the sake of the argument, I am assuming that this is not something the Martians are capable of.

[5] Ibid, 445.

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  1. bwinwnbwi
    09/05/2010 at 7:26 am

    I’m not sure if a moth is like a robot or not, but, in order for an objective account of consciousness to occur that account would have to be agreed upon by organisms that can understand different points of view and agree on the similarities and the differences that “can be identified” in that particular point of view; that said, humans are in that category. Humans and aliens are both conscious “if and only if there is something that it is like to be that organism.” My comment below explains what an objective account of consciousness means to me (thanks for the opportunity to post).

    I take exception to the total reduction of consciousness to physical causality; that said, there is a place for physical causality in consciousness. Here are my four questions (and answers) which, hopefully, make this assertion more clear (thanks for the opportunity to post):

    Q. What kind of automaton, e.g. the brain, a computer, a cell, and so forth, could generate consciousness?

    A. The kind of automation that could generate consciousness would be a structure that evolves both in time (in terms of complexity) and outside of time (in terms of logical implication) and ends up in the experience of the “implicative affirmative of the not-me-self” — or the loop of self-reference that continually implies “I”.

    Q. What is the what, how, and why of consciousness?

    A. Purely physical explanations work for the what and the how of consciousness because the why of consciousness is embedded in the physical event of consciousness. But, it is in this physical event where you find also the “function of consciousness.”

    Q. What is the function of consciousness?

    A. As stated above, consciousness is an adaptation (many) in our evolutionary past. These adaptations, at the structural level of (b~b~bb), culminate in freewill, i.e. the implicative affirmative of the not-me-self. Free will is the defining characteristic of what makes humans human. Free will also allows for improvement of other skills, e.g. motivation, better flexibility (like learning), social coordination, and better cognition.

    Q. Where does the brain come in? How are your subjective experiences explainable by neurons and synapses?

    A. The short answer to the above question is that the physical processes used to explain our experienced environment are not independent of consciousness on any level. However, in the same respect, consciousness can’t exist independent of physical process either. (This is the source of the problem at the quantum level of experience–but that’s a story for another occasion).

    The language used below is probably not familiar. It is helpful, though, when one begins to see experience in terms of an evolving structured duality (think two-sided coin here)–the structure of universe/consciousness.

    Because synchronic structure rises on the back of negation, the liberation process is not limited to biological evolution. At the next synchronic level (the level substituting for the psychological/mind concept), a more evolved species of life is the result. On this higher structural level, when at one pole (the empirical side) continuity occurs in discontinuity and, at the other pole (the freedom side) discontinuity occurs in continuity, the experience of “mind” is produced. Diachronically speaking, the content embedded in this structure is the human experience of self-consciousness occurring in a physical event. Discovered in this structure is the potential to produce a great deal of content, but, the actualization of this potential takes place along the liberation path in the form of the objectification of self-nature and culture, (the reciprocal movement occurring between mind and event). Structure, at this level (the physical event of a thinking person), becomes the story of civilization (both in its “ups” and “downs”). Think of the physical event of a thinking person, first as unexposed film and second, via the illumination of the implicative affirmative of the not-me-self, as the film development into human history, the history of human freedom, i.e., the liberation of the human struggle to survive, overcome poverty, ignorance, injustice,–to overcome all the physical and psychological afflictions that subvert the actualization of human potential.

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