|H/t Julian Baggini, The Ego Trick|
René Descartes’s two substance dualism, which proposes that mind is a separate immaterial substance from body, has a number of conceptual problems that are hard to overcome, but it is in tune with many of our common intuitions about the way we are. It appears to us that there is a material world out there in four (or perhaps more) dimensions and it also appears to us that we have an inner world, comprising thoughts, memories, feelings and so on, that justify their own ontology but do not have any extension in space.
However, problems of interaction between these two substances are particularly difficult to overcome; Descartes himself threw up his hands at the problem when, in answer to the question "how can the soul be affected by the body and vice versa, when their natures are completely different?", he replied:
This is very difficult to explain; but here our experience is sufficient, since it is so clear on this point that it just cannot be gainsaid. This is evident in the case of feelings and so on.A poor reply from the usually thorough Descartes. Julian Baggini sums up the objection to dualism through Gilbert Ryle's explanation in The Concept of Mind:
They [dualists] started from the correct idea that thoughts, feelings and sensations were not physical things. The category mistake was to conclude that they must therefore be a different kind of thing, a non-physical thing. But there is another, more plausible alternative: they are not things at all. Rather, thinking and feeling are what brains and bodies do. Mind should not be thought of a substance, but as a kind of activity. (from The Ego Trick)So monist (one substance) ideas have become more accepted. Monistic idealism states that everything is at bottom derived from immaterial mind and monist materialism says that everything derives from matter. Idealism solves the interaction problem at a stroke, but also suffers from some of the other problems that plague advocates of the immaterial mind – problems of identity and other animals’ minds, for example. Materialism, or physicalism, has become the most favoured world view of late, but the task remains to reconcile our common intuitions with this physicalist view. By suggesting that thinking and feeling are what brains and bodies do, Ryle suggests a functionalist approach to solving this problem.
Advocates of functionalism argue that it acknowledges Cartesian intuitions about the mind but also allows for a materialist world view (although it’s not strictly speaking a materialist theory of mind since it’s also compatible with idealism). With other material theories of mind, problems have arisen when trying to accommodate the mental states with which we are all familiar with the material. Identity theories of the mind, for example, have contended that mental states are the same as brain states. This would mean that the idea of a red tomato, a mental state, is the same as a brain state. But it’s difficult to see how the grey matter that makes up our brain could be the same as the idea of a red tomato. It’s difficult to see how grey matter can be about anything, in fact, and this aboutness, or intentionality is a stumbling block for many materialist theories of mind.
So Functionalism proposes that the mind isn’t determined by what it is, but by what it does. That is, mental states are functional states. It proposes causal relations which are generated by sensory input (we see and hear stuff) and other mental states (we feel pain), which then cause behavioural output (we avoid obstacles), and other mental states (sadness, say!). Consciousness and intentionality, then, are causal relations generated by functional states. For example, if we are thinking about a red tomato, we see the red tomato, but then further, think we’re seeing the red tomato. This awareness gives us an advantage because we can then plan and revise our thinking about red tomatoes, and the world around us.
Some proponents think that this incorporates many people’s intuitions about our mental lives, per Descartes, but also gives an explanation of mental states that isn’t reducible to the physical, but can be implemented in the physical. Sidney Shoemaker, for example, says:
The view I favor is ...a radically ‘nonreductive’ version of materialism. Neither in the case of properties and states nor in the case of particulars will it hold that there is any neat mapping of our common sense mentalistic taxonomy on to the taxonomies of the physical sciences. In this it agrees with Cartesian intuitions. But the sense in which psychology (whether it be common sense psychology or scientific psychology) does not reduce to chemistry and physics is the same as the sense in which biology and geology do not reduce to chemistry and physics, and in which chemistry does not reduce to physics. No one doubts that the entities and phenomena that are the subject matter of geology, biology, and chemistry are ultimately composed of entities and phenomena that are the subject matter of physics. There is good reason to think that the same is true of mental phenomena. The philosophical task here is not to carry out a reduction but to make it intelligible that there is this compositional relationship. (from Warner, R. and Szubka, T. (eds) (1994) The Mind-body Problem: A Guide to the Current Debate, Blackwell, pp.55–60)This irreducibility of functionalism, if that's what it offers, dispenses with the brain-mind identity problem, since the functionalist mind could be multiply-realised – if the mind is what it does, then whatever hardware can implement these mental functions could be the platform for mind. Functionalism also fits well with natural selection as a theory of speciation, since a brain function that provides a benefit would be preferred, and we can explore how brain function might have developed accordingly.
So, the upshot is that Functionalism is compatible with the notions that prompt dualism, that the brain is not identical to the mind, and also with physicalism, because brain functions can be implemented in the physical. However, some objections to Functionalism have been noted.
Frank Jackson’s knowledge argument highlights a major objection to functionalism. Imagine a person, Mary, in a room completely washed of colour – a black and white room. Mary could be taught everything there is to know about colour so that she functions as if she can see colour. However, when she emerges from the room for the first time, there is something new she will learn about colour – what it feels like to see red, for example. This suggests that functionalism does not account for qualia (colours, taste etc), because Mary was functioning fine without this colour knowledge. So we can see that there is something about redness that seems superfluous to Mary's adequate functioning. Why do we have this sensation if our minds are purely functional? If we could function without redness, why has evolution delivered that sensation, and how? There appears to be no advantage to operating with or without redness, if this thought experiment is to be believed, so it could not even be selected for.
inverted qualia argument; twins could experience colours diametrically opposite (one sees black as black, the other as white, one sees red as red and the other as blue) but these differences are in no way reflected in the functioning of each twin. They will both behave the same way with inverted qualia, which leaves us wondering what relevance the actual qualia experience has to function. What is the function of the colour qualia? And, once again, how can we explain the evolutionary benefit of different colours if they have no functional difference?
Ned Block also proposed the China Brain argument; he imagined hooking up the entire population of China to behave as neurons do. If this configuration functioned in a way that the mind does, but apparently without qualia, then, again, what is the functional value of qualia?
Functionalists counter that qualia are functional too, so would deny that these thought experiments are valid, but it’s clear they have some work to do to back up this contention. Frank Jackson himself reflects the thoughts of many philosophers when he gave up his own Mary's Room argument, writing:
Most contemporary philosophers given a choice between going with science and going with intuitions, go with science. Although I once dissented from the majority, I have capitulated and now see the interesting issue as being where the arguments from the intuitions against physicalism—the arguments that seem so compelling—go wrong.Jackson rejects the knowledge argument because he believes that the nature of colour experience is illusory:
...my argument will involve the claim that we are under an illusion about the nature of colour experience, an illusion that fuels the epistemic intuition.He accepts a Representational Theory of Consciousness, in short. He notes that qualia and so on are diaphanous - they are a little vague, variable and unclear:
I think, with the current majority, that ['experience is a representation'] is the right way to think of the lesson of diaphanousness. My reason is that perceptual experience represents. My experience as of a round, red object in front of me represents that there is a round, red object in front of me. I may or may not accept that things are as they are being represented to be, but I take it as axiomatic that each and every sensory experience represents that things are thus and so.... but that is beyond this piece (and possibly me!).
Functionalism powerfully accounts for our common Cartesian intuitions about the mind while not falling into the problems that plague identity theorists. However, it is in danger of being too liberal as a theory, allowing too many examples of the operating mind than would seem plausible. And more work is needed to explain intentionality and qualia through the notion of mental states as functional states, to confirm the defeat of knowledge arguments.
Bibliography (not otherwise linked):
Wilkinson, R. (1999) Minds and Bodies , Milton Keynes, The Open University