Are psychology and materialism compatible?

Lecho asked:

Are Psychology and Materialism compatible?

Answer by Danny Krämer

This question boils down to the question of the relationship between psychology and the other natural sciences. Descartes famously argued, that body and mind must be two very different substances. But since the scientific revolution, it is difficult to defend some form of dualism. How should the two substances interact — and they for sure do, because I can consciously move my body by thinking about it — without contradicting the natural laws like the law of energy conservation? But it is also a difficult question how a materialist worldview can explain the mind. I will talk now about some materialist proposals. I start with the theories that I find rather unplausible and end with the one I think is the most promising.

First, there is eliminative materialism. This form of materialism argues, that the predicates of our folk psychology, like belief, wish or desire are empty. When we talk about the behaviour of other people, we explain their behaviour by reference to their beliefs and desires. The eliminative materialist says, there is nothing like a belief or a desire that can be identified by neurobiology. These concepts are like the concept of phlogiston. They are concepts of a bad theory and when we have a better theory we can drop these concepts altogether. So materialism is not compatible with folk psychology but with a psychology to come, the eliminativist argues. I think that is just a very bald speculation about the future of science. Today there is no reason to believe, that our best psychological explanations will not contain the concepts of our folk psychology. Most of psychology is belief-desire-psychology and neurobiology is not even close to explain the complex behaviour of human beings without the concepts of beliefs and desires.

The reductive materialist is something more liberal. He thinks there will be a theory reduction. Psychological predicates will be reduced to predicates of neurobiology and in the last instance to physics. What does this mean? Let’s take the predicate “pain”. The reductive materialist thinks that the predicate “pain” will be identified for example with the predicate “c-fibres firing”. Every time someone is in pain her c-fibres fire. Do this reduction with all psychological predicates and you have a reduction of psychology to neurobiology. Psychology and Materialism are compatible because the predicates of psychology are coreferential with some predicates of physics. But there are some problems with this proposal too. For example, pain may be realised in humans by firing of the c-fibres. But what about an octopus or a martian? They do not even have c-fibres but they may still be in pain — the octopus shows clearly pain behaviour if you hurt him. That is the so called argument from multiple realisations.

How to solve the problem? The most promising form of materialism is, I think, nonreductive materialism. That means you believe that everything supervenes over the material, i.e. if you destroy all matter there will be nothing left. But you do not think there must be some theory reduction to make this claim true and you can bring good reasons why some predicates cannot be reduced to physical predicates. I think the reason for that is, that most of the predicates we use are multiply realisable. Take the predicate “money”. Money can be made of paper, metal and even bits on a computer. Most of the money nowadays is virtual money. But if you destroy all computers and all the cash, there will be no money any more. Or take “pain”. Pain is realized in humans, let’s pretend, by firing c-fibres, in martians maybe by some organ made of silicon. These are predicates that are more abstract than for example a predicate of physical science. “Electron” only refers to electrons. But “money” can refer to paper, pieces of metal or bits in a computer. What counts here is not the material but the role the thing plays in a wider context, or like Aristotle would say its form. But still: destroy all matter and there will be no money and no pain whatsoever.

So all these forms of materialism argue that Psychology and Materialism are compatible, and I think, some form of nonreductive materialism is true.


Naturalism vs. materialism

Carla asked:

What’s the difference between Naturalism and Materialism?

Answer by Danny Krämer

That question just jumped onto me. Here is my attempt to answer it. The easy part is materialism: Materialism is a position in ontology that states, that everything there is is matter. Of cause now you have to explain what you mean by matter and how some objects that make always trouble – like the mind, numbers, values – can be material. You can be a reductive materialist. That means, you reduce non-material things to material things. For example, you reduce mental events to physical events in the brain. But you can also be a non-reductive materialist. That means, you still believe that everything is matter but that you will not reduce mental talk to physical talk. A mental event, for example, is then not just a brain state but the brain state plus some external properties like its origin.

Now it is true that most of the naturalists are materialists. But modern naturalism was introduced by Willard van Orman Quine as an epistemological thesis. He said, ‘There is no first philosophy.’ That means we do not need philosophy to justifiy our scientific practice – as for example Descartes wanted to do. All we need to know something about the world is science. If we ask what exists, we should ask what our best scientific theories postulate. This is an epistemological point. But it has ontological consequences. When we ask our sciences what exists we get first of all the answer of physics. There are fields or particles and basically everything is made out of it. And then you have to do your ontological homework as mentioned in the last paragraph.

But a naturalist need not be a materialist. Actually, he is forced to give up materialism if there is good scientific reason to. If we would gather scientific evidence that there is another substance than matter then the naturalist must abandon his belief that everything is made of matter.


Cartesian dualism and consciousness

Tung asked:

Can Cartesian Dualism successfully account for the existence of consciousness?

Answer by Danny Krämer

I think, Cartesian Dualism makes consciousness even more mysterious than materialism. As you know, Descartes postulates two different substances. The res extensa is the substance of all extended bodies. The res cogitans is the substance of the thinking beings. This substance is not in space because it is not extended. The biggest problems are: First, how is it that a special (bit of) res cogitans (me) is bound to a specific piece of res extensa (my body)? You can only explain this by some supernatural story. Second, how can these two substances interact? When I think that I want to raise my arm (something the res cogitans that is me does) then I can ‘command’ my body to raise the arm. But how is that even possible if the res cogitans has no spacial extension? The res extensa is a closed system, as we know from physics. You can not get any energy in that was not there before. Descartes said, the soul steers the direction of the pineal gland and so the direction of the spirits. But that is also impossible as Leibniz pointed out. Not only the energy of a physical system is constant but also the impulse. There is in principle no way to understand how to make dualism a working hypothesis.

On the other hand it is very plausible that materialism in some form could be true. We see that our brain has a deep connection to our consciousness. We can do experiments to get a better understanding of the connection between brain and mind. Something that is just impossible in a cartesian picture. Even so we do not understand the complexities yet, it is at least imaginable that a materialist view of the mind could be well established some day.

The disjunctivist theory of perception

Bella asked:

What is meant by a ‘disjunctivist’ account of perception? What is the case for disjunctivism?

Answer by Danny Krämer

The interesting point of the philosophy of perception is: “How do we gain knowledge by perception?” Therefore there are three different kinds of perceptual experiences, that are often listed: veridical experience, illusions and hallucinations. The case for a veridical experience is pretty straight forward. If you look at a red tomato and you see indeed a red tomato, then you have a veridical experience of the tomato. An illusion is, for example, when you look at a red tomato but you see it as green, for whatever reason.  And a hallucination is when you see a red tomato but there is just no red tomato to see. Classical philosophy of perception maintains that all three cases have something in common (for example a sense-datum, a representation). Disjunctivists deny this point. A veridical experience and a hallucination of a red tomato have nothing in common. There is nothing like a red tomato representation in my mind, that is the same when I see a red tomato and when I hallucinate a red tomato.

There are many different arguments for the disjunctivist view of perception. The most popular origins from John McDowell and is an epistemological one. First, we recognize that it could be possible that we think we have a veridical experience tomato but in fact we only hallucinate one. Our claim that there is a tomato is therefore not really justified. But the factor that turns the veridical case into a hallucination is not epistemically accessible to us. We believe that there is a red tomato, because we saw it but in fact there is none. That means our epistemic reasons for perceptual judgements are not better in the veridical case as in the hallucinatory case. And this yields scepticism. McDowell takes a disjunctivist stance to block these sceptical arguments. If there is no common factor in the veridical case and the hallucinatory case, then we have different epistemic factors that play into our perceptual judgements. In the veridical case it is the thing itself and our perception of it. In the hallucinatory case it is something different in kind that creates the wrong judgement.