Descartes’ substance dualism

Question 1

What is Descartes substance dualism?

Answer 1

• The theory that there are two distinct substances, mental and physical.
• A substance is a fundamental type of existence which can’t be broken down into anything else.
• The essence of mental substance is thinking, the essence of physical substance is extension

A thing is extended if it takes up physical space, is located, has coordinates.

Question 2

What is Descartes’ indivisibility argument?

Answer 2

• Descartes argued that the essential property of physical substance is extension. Anything that is extended in space can be divided, because there has to be some point along which it could conceivably be divided.
• The mind does not appear to be divisible, however, because it seems to be non-extended. The mind is not located in space; it does not have spatial coordinates along which it could be divided.

Question 3

Leibniz’ law

Answer 3

Identical things must have the same properties.

If the body and mind were identical, then that one identical thing would be both divisible and indivisible, which is impossible.

Therefore, the mind and body are not identical.

Question 4

How would you structure this argument in a paragraph?

Answer 4

P1. Physical substance is divisible (since it’s extended).

P2. The mind is indivisible (since it’s non-extended).

P3. Leibniz’ law is that identical things must have the same properties.

C1. The mind therefore cannot be identical with any physical substance, such as the body.

Question 5

How may argue that the mental IS divisble?

counter-argument of the indivisibility argument.

Answer 5

• The mind can be divided into perception, memory, emotions and so on. So, the mind and body share the same property of divisibility and thus could be identical.
• This attacks P2, the premise that the mind is indivisible, in which case the mind does have the same properties as the physical body, making the indivisibility argument false.

Question 6

How did Descartes respond to the argument that the mind is divisible?

Answer 6

• Descartes responded that by the mind he means consciousness.

Perception, memory and feeling are not divisions of consciousness, they are different modes of consciousness.

• It is the same undivided mind that perceives, remembers or feels emotions.

Question 7

Further (and stronger) objection of the indivisibility argument

Answer 7

Divided hemispheres.

Question 8

What is the Divided hemispheres argument?

Answer 8

There are phenomena which have been discovered by modern psychology which could suggest that actual divisions of the mind are possible.

The brain is split into two hemispheres which are only connected by a thin strand of neurons called the corpus collosum, which can sometimes be cut as a medical procedure to treat epilepsy.

Question 9

What has been observed after cutting the corpus collosum?

Divided hemispheres argument

Answer 9

This has the bizarre effect of, some have argued, seeming to result in two separate ‘persons’ in the one body.

Patients have been observed picking up some food with one arm and the other arm hitting it away. One case involved a patient who tried to hug his wife with one arm and push her away with the other.

(The right hemisphere controls the left arm and the left hemisphere the right arm.)

Question 10

What does the divided hemisphere argument further cast doubt on

Answer 10

It also casts doubt on Descartes’ method in assuming that we have the full picture of what our mind is merely from how it seems to be to itself, which is his justification for P2.

P2 was the mind is indivisible (since it’s non-extended).

Question 11

What is the interaction problem?

countering substance dualism.

Answer 11

This is a criticism of dualism. If dualism is correct and the mind and body are separate fundamental types of existence, how is it possible for them to interact?

Question 12

Example of the mind and body interracting.

Answer 12

when the hand touches something hot it causes the mental feeling of heat. This requires non-physical mental substance to causally affect and interact with physical substance.

Question 13

Thermodynamics argument

countering substance dualism

Answer 13

Physicists say that the universe is ‘causally closed’ because of the second law of thermodynamics that energy can be neither created nor destroyed.

This means that energy cannot come from outside the physical universe and affect things within it. However that seems to be how substance dualism would have to work since the mental is supposedly outside the physical universe. Therefore substance dualism is false.

Question 14

Gilbert Ryle & the category mistake

countering substance

Answer 14

• Ryle claimed Descartes was making a category mistake.
• Descartes argues that since the mind is non-extended, indivisible and thinking, it cannot be a physical thing and must therefore be a non-physical thing.
• Ryle argues that conclusion does not follow.
  Just because the mind is not a physical thing, that doesn’t mean it must be a non-physical thing. There could be another option – the mind might not be a ‘thing’ at all, of any type!

Question 15

What is an example that could be used to illustrate Ryles category error?

Answer 15

Imagine someone asked ‘what is the taste of blue?’. That question involves a category mistake, thinking blue belongs to the category of things which have a taste.

Question 16

What does Ryle argue about the language we use to describe the mind?

Answer 16

• Ryle argues that the language we use to describe the mind confuses us about the logical category it belongs to.
• We use the word ‘state’ and ‘process’ to describe physical things, but also use those words to describe mental terms.
• Since only physical ‘things’ can be in physical states or undergo physical processes, we thereby confuse ourselves into thinking that the mind must also be a ‘thing’ as it can be in mental states or undergo mental processes.
• Descartes, on the basis of that confusion, finds himself unable to locate a physical ‘thing’ that could be the mind and so wrongly concludes that it must be a non-physical thing – mental substance.

Question 17

What other option does Ryle propose as opposed to Descartes assumption the mind is in the category of ‘things’

Answer 17

Our word ‘mind’ does not refer to a thing at all, it actually refers to a sets of behavioural dispositions.

Question 18

What does Ryle mean by disposition?

Answer 18

A disposition is a tendency for a thing to behave in a certain way under certain conditions. Ryle thinks that when we talk about the mind we are really talking about behavioural dispositions.

• For example if someone is described as scared, what is actually being described is their inclination (their disposition) to make scared facial expressions and run away.

Question 19

What does Ryle use in order to illustrate disposition?

Answer 19

• The example of the “brittleness” of glass, which is the disposition of the glass to shatter upon impact.
• Is the brittleness of the glass a ‘thing’? Where is the brittleness of the glass? Does it have extension, can it be divided? Clearly the answer to such questions is no
• just like Descartes answered to such questions when asked about the mind, yet we dont feel inclided to draw upon the conclusion that brittleness of glass is a non-physical thing.

Question 20

What is a criticism of Ryle?

Answer 20

• However, is the mind really a set of dispositions? Doesn’t it ‘feel like’ something to have a mind?
• Reducing the mind to a set of dispositions doesn’t seem to satisfactorily capture nor explain the fact that conscious awareness at least ‘feels’ like it ‘exists’ in some sense.
• it seems overly reductionist and minimal to regard it merely as existing as dispositions to behaviours.

Ryle was a philosophical behaviourist which is a controversial version of materialism.

Question 21

In defence of Ryle

Answer 21

Ryle might be wrong that the mind is a set of dispositions, but he’s arguably still right to point out Descartes’ assumption that because the mind is not a physical thing, the only option is for it to be a non-physical thing.

• Who knows what other options there could be, aside from dispositions. Descartes’ conclusion at the very least requires much more justification than he gives.