Cont: Functionalism and consciousness

According to functionalism, one might be tempted to say that a conscious system is a computational system that is capable of posessing functional properties. If we consider Bill Gates, aside from his obvious physical properties, the kinds that any physical thing might have (e.g. his weight, height, his particular chemical composition), one can attribute various properties to him: he is Chairman of Microsoft; he is a computer programmer, etc. Each of these properties are functional properties, and by virtue of having them he is conscious.

Of course, going by that definition, a pocket calculator could be said to be conscious. So it seems that to answer the problem of consciousness, functionalism needs more than a theory of functional processes and properties. Intuitively, consciousness seems linked to the ability to posses functional properties that are capable of producing qualitatively different mental phenomena, what some philosophers refer to as qualia.

But it seems entirely possible, and coherent with functionalism, to suggest that two people could experience entirely different qualia with exactly the same equipment, e.g. two people with the same visual "equipment" could see a block of colour; one could see "red", the other "green" (putting linguistic considerations aside). This phenomenon is known as inverted qualia, and poses no problems for functionalism as such. In fact, in Inverted Earth Ned Block pointed out that one could conceivably render someone unconscious, invert their visual equipment and put them into a room that is identical to that of a second person except that all colours are reversed; in this situation, their qualia would be identical, since what it would be like to experience the colours would be identical for both people, despite their hardware and the reality they are seeing being opposite to one another.

However Block also raised several problems with qualia that affect functionalism in particular. The first is to say that if we accept that inverted qualia pose no problems to functionalism as such, then we must also accept the logical possibility that my visual qualia in a given situation might be identical with your auditory qualia in a given situation, since there is no necessary connection between qualia, the person's hardware and the environment that is 'causing' the experiences. This is both perplexing and attractive to those who feel materialism to be too inhuman, since it suggests that my listening to Beethoven's 5th symphony and your reading a novel set in the Napoleonic wars could evoke exactly the same mental phenomena; what is is like for me to listen to the music could be identical to what it is like for you to read the book. Romantic as this seems, it does make explaining functional states and properties extremely difficult, as you can no longer use the hardware nor the environment as a reliable reference point.

There may also be mental states that aren't public, such as unconscious states, and so that functionalists cannot accurately describe nor explain, at least not objectively, since they cannot get any reliable information by interacting with the owner of the states, they can't look at the brain states, and they can't rely on the subject's environment.

One can also posit the existence of zombies, unconscious beings that have the same behaviour and the same brain states as a conscious being, but no qualia. The functionalist ought to be able to distinguish a zombie from a conscious person, but given that all of the public information seems identical to that of a conscious person, how could one ever know? How could we know everyone else isn't a zombie, or that we ourselves aren't zombies? By being so liberal about qualia and their relation to the brain and the subject's environment, functionalism solves a lot of the problems associated with behaviourism and identity theory, but it also opens the door to extreme forms of scepticism, and makes it extremely unlikely that it could deliver any scientific explanations of the functioning of a specific mind-brain.