Lecture 9

Functionalism

Physicalism: the thesis that mental states either are or supervene upon physical states.

If that is what physicalism is, is there an alternative?

The answer that leaps to the tongue is: dualism. But what I have in mind is Dennett's remark (in Consciousness Explained):

'accepting dualism is giving up.'

Dennett, EC, p.37.

The damning difficulty with dualism:

It breaks with the fundamental physics that if change of motion occurs, energy must be expended. When the mind moves the body, as dualism suggests it does, where does the energy come from?

(Dennett, CE, p. 35)

It is tempting, so some of you find, to go beyond epiphenomenalism. Yes, you say, brain processes give off thoughts sometimes. But also, sometimes, those thoughts bear back on brain process and alter it. There is a two-way process. And you put this forward, some of you, as though this is a bit of a minor revision to epiphenomenalism.

Surely this is the most plausible view. The brain is the grounding of thought, but once generated thought is not entirely impotent. It can in turn make a difference to brain process. And surely this is the straightforward thing to believe. I have thoughts, and sometimes these can affect what I do. I form such and such a belief, and that belief helps determine what action I undertake.

There is an enormous difficulty with this however. To make a change in the course of events energy needs to be expended. When a thought makes a difference to brain process, where does the energy come from? Are we to say that people who think a lot about what they do, and alter their brain process frequently through thought, add more energy to the universe than the couch potatoes?

Take again the position that I think is tempting to many: brain process may produce a thought, but then that thought may act back on process.

But that is only important, presumably, if the thought produces by brain process takes off on its own, generates a few or a lot more thoughts, the end product of which bears back upon brain process.

BRAIN PROCESS

thought

is not very interesting. What seems really interesting, a break with physicalis is if you have brain process producing a thought which then generates more thoughts on its own before bearing back upon brain process...

BRAIN PROCESS

thought > autonomous thought process

But on this picture, thoughts can occur on their own, or at least stimulated only by other thoughts. Many of them now are not tied to processses in the brain. The break with epiphenomenalism is much more serious than it at first appeared.

We have introduced something that looks like a complete mystery, how one thought generates another,

as well as something that breaks with the idea that to have a change in motion you need a source of energy.

So this dualism idea seems to break with science. And maybe that is what those who defend it want.

Picture in Dennett p.38.

Functionalism

Scientifically-minded people are sympathetic to the claim that thoughts are to be identified with states of the brain: identity theory.

Or with the idea that thoughts are given off by states of the brain as a kind of effluent: epiphenomenalism.

The temptation with both these approaches is to think that a token thought either is, or is given off by, a particular brain state.

But what do I mean by a particular brain state?

Possibly: think of opening up a brain and pointing to a particular bit of it, a particular network of interconnecting neurons.

My twinge of toothache is the the firing of that particular network. When that particular network goes active, I feel a twinge.

The identity theorist says: because that is what the twinge is.

The epiphenomenalist says: because that is what gives off the twinge.

Let me put this in the concrete terms that you find in the literature. It used to be thought that there was a particular kind of neuronal link that was associated with pain - what they called the c-fibres.

When the c-fibres were firing you felt pain. If they weren't, you didn't.

Assume this is still a plausible hypothesis.

Then you might say, if you were an identity theorist, the firing of that batch of c-fibres is the pain.

Or you might say, if you were an epiphenomenalist, the firing of that batch of c-fibres gives off the pain.

So you would say, the physical side of pain, or the physical grounding of pain, is the firing of the c-fibres.

But this position was thought to be vulnerable to the following objection: It seems to rule out creatures who lack c-fibres from having pain.

Supposing you found a sort of animal on another planet, which seemed to behave very like badger, but which turned out to be made of silicon or something, with not a c-fibre to its name. If pain simply was the firing of c-fibres, we could never entertain the idea that this new creature might be capable of feeling pain. Or if we took the epiphenomenlist position that pain was a mental state that was produced by the firing of c-fibres, again we would not be able to think of this Martian creature as capable of pain.

Or think not of a Martian badger-type creature made of silicon, but of one of our own dolphins. A very sophisticated animal we might think, and then discover that its nervous system was not at all like ours; and in particular that it didn't have any c-fibres. Again if it were true that pain is or is grounded in the firing of c-fibres we wouldn't be able to think of the dolphin as capable of feeling pain.

BUZZ: do you think that a creature with a very different nervous system from our own might nevertheless feel pain? Does this prove physicalism wrong?

These implications of physicalism, in the two forms considered, were held by some to be unacceptable.

The functionalist theory was put forward to remove this type of objection.

Pain, it was said, might be associated with c-fibres in humans, but that would be because of the job c-fibres performed. In another creature, the role played by c-fibres in us might be performed by something else. In that case, pain would then be associated with whatever was the 'equivalent' of c-fibres.

I've explained this in terms of pain, but the functionalist approach generalises the point.

It looks on the brain and nervous system as a machine capable of being analysed functionally. That is to say, we can look at it as made up of a set of subsystems, each of which does a particular job in keeping the system as a whole working.

A running car would be a simpler example of something we can analyse functionally. There is a system to feed fuel into the cylinder, a system to keep the pistons positioned ready for each explosion, a system to transmit the upand down movement of the pistons to the wheels and so on.

In any particular car, each of these is done with a particular piece of hardware. The pistons for example might be aluminium in one model and steel in another. Different materials, maybe a different arrangement: but same function.

From the point of view of functional analysis, you could say that cars with petrol engines are all functionally the same. There are lots of differences in how in detail the functions are carried out., but carried out they are. If it is a petrol engine something has to feed the fuel into the cylinders. That is a function that has to be performed. And there are plenty of others - functions that have to be performed if the car is to keep running, but functions which might be carried out in a wide variety of different ways, using different materials, and different designs.

Often what is said is that the same function may be realized in different ways.

BUZZ Can you think of examples of where the same function is realized in different ways?

It has long been suggested that we should think of the brain in the same way - as a machine which it is sensible to analyse functionally. This bit does this, that bit does that.

The functionalist theory of the mind holds that mental things are tied not to particular ways in which functions are realized but to functions.

Let me return to the particular example of pain.

Suppose the brain needs a warning function to be realized. It needs some way of alerting the system to danger. We can suppose that it is the system of c-fibres that realize this function in the human brain.

Other creatures will need the same function carrying out. But they may evolve quite different ways of having that function performed. The same warning function might be realized in a different way in a dolphin, or Martian badger.

The functionalist theory of pain would the be that pain is tied not to the c-fibre system as such but to the warning function that the c-fibres happen to perform in human beings. If you are a creature with a different way of realizing the warning function, you will feel pain when your (differently realized) warning system is activated.

Now just think of the c-fibres that are in me, and assume I have toothache. Those c-fibres are firing, and there firing is, or is the physical grounding of, my pain.

But if the functionalist is right it would not be correct to say simply that pain is the firing of c-fibres. In a silicon-based creature, it might be the activation of the frontic nexus that performs the warning function. In that case if you take a particular creature with toothache, its pain will be, or will be grounded in, the activation of its frontic nexus.

So if we are trying to say what pain is, we shall have to distinguish between the pain that a particular creature has (eg me, or the Martian badger) and pain as a phenomenon that transcends particular cases.

There is a piece of jargon that is supposed to help in cases like this, which I had better explain.

TOKENS

Suppose I am told that the pie costs £2.

I have £2 in my pocket.

You have £2 in your pocket.

Which £2 does it cost?

Well - either. When you say a thing costs £2 you leave it open whose or which £2!

A piece of jargon is used when it matters in philosophical contexts whether you are saying the £2 in my pocket or the £2 in general as it were that the thing costs.

I have a token £2 in my pocket. You have another token £2 in your pocket. The general £2 in the assertion that the pie costs £2 doesn't refer to a token at all. It is saying something more general.

Similarly, take the belief that Fodor is a difficult writer. Some people say if you have that belief, and I have it also, then you have a token of that belief in your mind or head, and I have another token of the same belief.

BUZZ

Write down a sentence in which a token intention is referred to. And another in which an intention but not a token intention is referred to.

I intended to wash the cat.

Lots of people intend to wash their cat regularly, but they don't get round it it.

Use 'type' for the general thing as opposed to the token:

TOKEN AND TYPE MENTAL STATES

Now let me use this distinction to help state more clearly the functionalist account of pain.

Token physical states ground token pains.

Type-pain is grounded in the function performed by those physical states.

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THREE LEVELS OF DESCRIPTION

The type/token distinction also helps me make another point.

Think of the netweork of c-fibres in me and the token-state they are in at a particular time.

I can offer a neurophysiological description of that state. (Arrangement of neurons, their size, their activity etc)

But if the functional perspective on the brain is right, I can say a second thing about that system of c-fibres in me: it is realizing a function.

Compare: two descriptions of the lung: apice of tissue of such and such a size and weight, with such and such an internal structure.

An organ for getting oxygen into and out of the body.

Two descriptions, but one thing.

BUZZ: another example?

So that one and the same system of c-fibres has

a neurophysiologcal description, and

a functional description.

There is a third thing. That self same system of c-fibres in a certain state of activation may also be, if the functionalist is right, a pain or the physical grounding of - a token pain.

So three levels of description of one physical system:

neurophysiological (physical)

functional

mental

Notice though that the mental description, on the functionalist view, is attributable in virtue not of its physical nature, but of its functional role.

So for functionalism there is a divorce, though of a subtle kind, between mental and physical.

The physical supports the mental, but only in virtue of the function the physical performs.

Lycan puts it like this:

'And so there is after all a sense [if functionalism is right] in which 'the mental' is distinct from 'the physical': though there are no nonphysical substances or stuffs, and every mental token is itself entirely physical, mental characterisation is not physical characterisation, and the property of being a pain is not simply the property of being such and such a neural firing.'

Lycan, Mind and Cognition, p. 8.