Substance Dualism

Question 1

What is Descartes dubitability argument?

Answer 1

1. I can doubt whether I have a body or whether anything material exists,
2. I cannot doubt the existence of the thinking mind which is thinking these thoughts now,
3. So the body has a property which the mind does not have,
4. Therefore the mind and the body are distinct substances.

Question 2

What counter-argument is given to the dubitability argument?

Answer 2

1. Person A is certain that Cassius Clay is a boxer,
2. Person A is not certain that Muhammad Ali is a boxer. Therefore, a property (person A being certain that something is a boxer) belongs to Cassius Clay but not to Muhammad Ali,
3. Therefore, Cassius Clay is not the same person as Muhammad Ali,
4. However, Cassius Clay is the same person as Muhammad Ali; therefore the argument goes from true premises to a false conclusion, with the same form as the dubitability argument.

Question 3

What does Descartes mean by the mind is indivisible?

Answer 3

Descartes argues that the mind cannot have any part, any faculty, away or it would cease to exist.

Imagine your single stream of consciousness, your senses, thought, feeling, imagination, etc., divering into several streams while still all remaining yours. To Descartes, this is nonsense, it is literally to try and imagine an impossibility.

Question 4

What is Leibniz’s law?

Answer 4

If, for all properties P, P(A) if, and only if, P(B), then A=B.

If two things have the same property they are the same thing.

Leibniz’s law determines identity in terms of having identical properties.

Question 5

Leibniz’s law applied to the mind and physical?

Answer 5

1. If object A has property P, and object B does not have P, then A is not the same thing as B,
2. The body/brain is divisible,
3. The mind is not divisible,
   C. The body is not the mind/body.

Question 6

What medical example seems to disprove the notion that the mind is not divisible?

Answer 6

1. Corpus Callosum surgery,
2. Patients shown a picture of a green apple to their left eye and not to their right eye,
3. They will then be asked what they saw,
4. The consciously speaking individual will maintain that they do not know, when pressed to guess or imagine, they will, however invariably say they saw a green apple, while maintaining that they have no memory of the relevant perception.

Question 7

What does Hume argue against Descartes?

Answer 7

1. Descartes, as Hume claims, maintains that ‘we are every moment intimately conscious of what we call our self; that we feel its existence and its continuance in existence’,
2. Hume responds that we do not have an impression of the self. The only thing he claims we are actually aware of is a stream of conscious experiences and their contents, ultimately reducible to simple impression and their complexes.

Question 8

What other argument is made against Descartes mental/physical property distinction?

Answer 8

1. That not all that is physical is divisible,
2. Therefore, non-divisibility, even if applied to the mental, is not a unique characteristic of it, hence it would not be sufficient to say that something is non-physical by identifying the property of non-divisibility,
3. Some might identify more immediate, phenomenal cases such as cold, heat, walking, etc.. We might maintain that these cannot be split in two. However, we wouldn’t argue that this then makes these non-physical.

Counter: Possible to argue that while we cannot divide, e.g. walking into two walkings, we could conceptualise it physically in some way such that we would be able to speak of dividing it into physical constituents.

Though could we not apply this line of reasoning to the mind as well? So while we might not be able to divide the mind into two minds, we might nevertheless still maintain that the mind can be divided into mental constituents.

Question 9

What is Descartes’ conceivability argument?

Answer 9

1. If I have a clear and distinct idea of two things/essences separately, then it must be logically and metaphysically possible to separate them,
2. I clearly and distinctly conceive the mind to be a thinking and un-extended thing,
3. I clearly and distinctly conceive the body/physical/material as extended and unthinking,
4. The body and mind can therefore be separated and are distinct substances.

Question 10

What counter-example to the conceivability argument does Antoine Arnauld give?

Answer 10

1. Asks us to think of someone who does not know that the pythagoram theorem for right-angled triangles is true,
2. Such a person might think that it is conceivable for it to be false, therefore logically possible,
3. However, Arnauld points out, this seems like a metaphysically necessary theorem, and so it is metaphysically impossible for it to be false. Not even God could make it false,
4. Arnauld then supposes that this is comparable to Descartes’ argument. It may be that Descartes thinks himself to have a clear and distinct impression, this does not mean that it is genuinely metaphysically possible for the mind to be separated from the body.