14. Contemporary Philosophy of Mind: Dualism and Materialism

In this final lecture we are going to dip our toe into some contemporary debates regarding the nature of the mind and its ultimate constitution.

Recall that Descartes argued that the mind and the brain were two distinct substances. The mind is a non-physical thinking and the brain a physical non-thinking thing. So these two things were mutually exclusive.

His argument for this was a conceivability one:- Since it is 'clearly and distinctly' imaginable that I could exist without my body, I am therefore not my body (these are separated). So if mind and body were really the same thing it would be impossible to even imagine them existing separately. - He also offered another argument for this - the mind and brain have different properties. The mind doesn't seem to be located anywhere, it doesn't seem to have parts, whereas physical objects by their nature have parts, they can be divided, and they have a front part and a back part, but there is no front part to your conception of milk. Descartes therefore thought they were completely distinct substances.

- This is what we call Descartes substance dualism. But there is a problem with this kind of view.

One major problem is the problem of mental causation.- It seems intuitively obvious that mental events cause physical events and vice versa. The mind and the body interact all the time. This is what philosophers mean when they say this common sense view of mental causation is part of our folk psychology.

Folk Psychology

Folk psychology can be seen as a theory held by the average person about the way the mind works. This theory helps us to explain and predict the behaviour of other people.

- We have a system of concepts.-These are the concepts of belief, desire, pains, itches, tickles, hopes, fears, anger, jealousy etc- Descartes held that we had immediate access to these mental states in introspection. (introspection means looking inside)

- We use these concepts about people internal states, to explain and predict the behaviour of others.

- These concepts develop naturally at a certain state of development.

This idea is a very radical shift in way of thinking and it comes out of work in the early 20th century known as behaviourism.

for example - the false belief test. We have 2 containers (one red and one blue) and a cookie. You see the cookie being put into the blue container. Now a person comes along and takes the cookie from the blue container and puts it in the red one. Now they ask you - the person who has observed all this - assume someone, Jimmy, comes

along and they see the cookie go into the blue container, but didn't see it being transferred to the red one. Where will Jimmy look for the cookie? Obviously they will look in the blue container. The surprising claim that psychologists come up with is that kids of a certain age fail this test. They cant understand the idea of Jimmy having a false belief. They often say that Jimmy will look in the red container, because they are just thinking of how the world is, not how it appears to Jimmy. They don't consider Jimmy's internal state and what Jimmy knows. So to pass the false belief test you have to be thinking about what the other person beliefs and knows and what roles these mental states will play in the other persons mind and using that as a basis for explaining and predicting behaviour.

Back to Descartes..

- Descartes thought that the pineal gland was where the mind and the brain communicated. This was because it was at the centre of the brain and is the only structure that is not duplicated on both sides. So Descartes thought this could be where it all came together. And hypothesised that movement in the brain, caused in a mechanical way by material bodies, resulted in an experience of pain, a belief, a desire etc.

- But if the mind is non-physical how can it be affected by anything that is physical? At the time of Descartes they assumed that causal actions happened by physical interactions and contact.

- Physical things cause by bumping into other physical things.- How can anything bump into a non-physical mind?- How can a non-physical mind bump into anything physical.

Unless you have this notion of cause and effect as requiring direct physical contact, you don't really get this problem of causation. Things causally interact in all kinds of ways and so this would just be a new kind of way and there is nothing really fatal to this idea. It really is only because of a certain conception of how cause and effect work, which may or may not be true.

But in modern times there seems to be a more scientific argument against dualism, and this is something that came out of the discoveries of physics. Causal closure.

- Physicists posit conservation laws for mass and energy. Mass is not created or destroyed. So its a self contained system where nothing gets in and nothing gets out. So we can sum this idea up by saying that everything that happens in the physical world has a cause that is itself physical because of this closure of the causal system.

- But if this is the case how could a non-physical thing causally interact with a physical thing? If it did there would be some unaccounted for energy in the system, which we don't find. This has led to materialism: everything is completely made of the postulates of a completed physics.

- Causal closure is itself a scientific discovery and there is some debate about whether it is true and we have enough evidence for it, but generally speaking some form of argument about causal closure is probably the strongest argument against substance dualism.

So after a foray into behaviourism, which we wont discuss this, and instead we will discuss a view that came around in the 1950's...

Identity Theory

- A reductive identity theory. According to this view the mind is identical to the brain. There are not two things; the brain state and the pain. They are one and the same thing.

- These philosophers appealed to other theoretical reductions. eg People had known about lightning for a long time. But no one really knew what it was until we discovered electricity. So there is not two things there, the lightning and the electricity, they are really only one thing. So they pointed to this as analogous to the mind. This happens all the time in science, we have things we have common sense views about and then we find out with science the true nature of it.

- So once we understood lightning then we were able to posit a theoretical identification. Lightning=electrical discharge. We then had 'reduced' the concept of lightning to the concept of electrical discharge. So the basic idea is that you reduce two theories that use different terms and show they are talking about the same thing.

So these philosophers thought we could do establish theoretical identities like this between the mind and the brain, but taking folk psychology concepts and aligning them to neuroscientific concepts. eg pain = c fibre firing; belief = brain state 65n

- Thus the goal of the identity theory was that we could ultimately reduce the concepts of folk psychology to those of neuroscience, by providing theoretical identities between the two theories that would allow us to translate one theory into the other.

Of course we cant do it now, but the idea was that we would be able to do it at some point. The neuroscience of the future would have to fill in the placeholders in the right side of the equation.

But the identity theory ran into an objection from what is called 'multiple realizability'. Consider the property of being in pain. Identity theory says that there is one brain state that is identical to pain. So pain is just this one particular thing happening in the brain. So if you don't have a brain, then it is impossible for you to have a pain.

But it seems possible to suppose that we discover alien creatures that did not have brains. Suppose they were a silicon based life form, or even that operated on simply hydraulics. Since this creature doesn't have a brain, identity theory says that it cannot have pain. But we can imagine that the creature gives us every other reason to think that it does feel pain. If that is possible, then it can't be the case that the brain simply is the mind. So it seems weird to rule out automatically the claim that we will never find any such thing like that when we really don't have any evidence for the idea that consciousness is the same thing as a brain.

- And also, isn't it strange to think that there will be one state that dolphins, cats, humans, monkeys, rhino's, squid, whales, etc all have in common? That seems a bit far fetched.

These issues with identity theory led to another way of thinking about the mind, which is probably the more dominant view currently...

Functionalism

To help us understand the main claim of functionalism lets step back and think of something else which is not mental.

- Consider the property of being a pump. It is not necessary that a pump be made in any one way. There are many ways to make pumps and many different materials that you can use to make those pumps.

- What is important to being a pump is not what you are made out of, but the function or role you play in a certain system. To be a pump is to have the function of pumping.

So too, beliefs are function role states in this view. To be a belief is to be caused in the right way and to have other causal connections to other mental states. So too for pain. Pains are the states that are caused by hitting, burning, stabbing, etc and they usually cause crying, stomping, distraction etc.

So this is the basic idea that functionalists have about the mind. That the mind can be characterised in functional terms and it leaves open the possibility that we can have computers and aliens with minds. Functionalism in its many forms, is very popular, but of course it has its problems as well.

One of the problems is that people think functionalism doesn't have a very good job of capturing consciousness. They bring up the problem of inverted qualia. Two people could have functionally identical brain state, calling all the same things 'red'. But one of them may have a very different conscious experience than the other.

This brings us to Churchland.

Eliminativism

Churchland is an elminativist. He thinks that identity theory and functionalism both suffer from the same flaw which is that they take folk psychology to be correct.

- The reductionist thinks that the terms of folk psychology can be reduced to the terms of neuroscience. There is a one-on-one correspondence to the terms. 'belief', 'desire', 'pain' etc and the terms specify certain brain states.

- The eliminativist thinks that it is going to turn out to be the case, that folk psychology is drastically mistaken. The eliminativist thinks that there are no such things as beliefs, desires, pains and the like. So in this view, folk psychology will have to be eliminated, not reduced. These are all terms from an outdated theory known as folk psychology. Churchland will take this view against functionalism as

well. There are other views about eliminativism. For example Daniel Dennet is thought to be an eliminativist about consciousness. This is a hard view to understand because what do you mean there is no such thing as beliefs etc. Why would anyone think this could be true?

This idea seems to go against common sense. But Churchland counters that what we consider to be common sense depends on what theories we accept as true. To us it is common sense to think that the Earth moves and that objects are inanimate and inert. But this wasn't common sense for Aristotle. So for Aristotle when he looked at the world he would have seen something different to what we see, because what we see seems to be dependent on what kind of theory we take. So it can't be dismissed only because it goes against common sense because common sense can turn out to be wrong.

And Churchland wants to also say that every other folk psychology theory has been supplanted by scientific theory and those theories dictate what we now think of as common sense. Churchland also says that he thinks eliminativism is what science does. It makes it necessary to eliminate a theoretical term. Churchlands favourite example is phlogiston. This is an example where the term got eliminated.

Phlogiston was a theoretical terms that was supposed to name a fluid 'caloric fluid' which carried heat. So when something burned it was theorized that the object was releasing phlogiston. But we now know that there is no phlogiston. There is nothing for us to reduce phlogiston to. Rather we eliminate it from our theory of combustion. Churchland thinks that this will inevitably happen to folk psychology.