Substance Dualism

Descartes’ version of dualism that characterises two different types of existence as two different substances, mental and physical. A substance is a type of existence which cannot be broken down into anything further. Man is created by God and consists of two ingredients: a body and a soul.

Descartes lays out his theory for Dualism in quite a neat way, he does it in 3 parts which I think fit neatly into 3 paragraphs. Each part has strengths and weaknesses. So I feel like Descartes basically writes your essay for you!

What exactly is Dualism?

Dualism refers to the distinction between two fundamental types of substance in the universe: material and thinking.
It is the opposite to physicalism, which states that all existence can be explained physically.
For Dualists, not all of existence can be explained physically. There are some non-physical parts.
Descartes argued that the mind and body are fundamentally different types of entities. The mind is characterised by thought, consciousness, and self-awareness, while the body is characterized by extension, shape, and motion.
For Descartes, the mind and the body can causally influence each other. In other words, your mind can affect your body, and your body can affect your mind
This type of Dualism is called Interactionalist Dualism because of that interaction between the mind and body. Descartes believed this happened in the Pineal Gland.
It's also important to note that mind and soul are used interchangeably for Descartes.

Descartes' Indivisibility Argument

We've already seen that Descartes believes that existence is separated into 2 substances: the material (physical) and the thinking (mental).
Both of these substances have defining features. The physical is characterised by shape, movement and extension. It literally occupies space and it can be continuously divided into halves.
The mind does not appear to be divisible because it is non-extended. It not located in space; it does not have spatial coordinates and it can't be divided.
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.
Back this up with: Leibniz’ law: This says that identical things must have the same properties. The physical has the property of being divisible but the mental does not. Therefore, the physical and mental do not share the same properties and so the mind and body are not identical.

Criticism: The Mental is Divisible

The mind has many parts to it, it's responsible for thoughts, memory, emotions, imagining. Maybe this is a potential way to divide it. If so, the mind and body would share the same property of divisibility and thus could be identical.

Descartes that all of the above examples are not actually divisions of the mind. Instead, they are different modes of consciousness. It is the same undivided mind that operates in all these ways.
However, discoveries in modern science, neuroscience and modern psychology suggest that actual divisions of the mind are possible. The brain can be divided into two hemispheres. The right hemisphere controls the left arm and the left hemisphere the right arm. Even the subconscious mind can be divided into the Freudian structure of the psyche - the Id, Ego and Superego.

I've heard from a lot of people that this argument can be quite confusing so I'll explain in more detail on this side.

P1. I have a clear and distinct idea of myself as a thinking non-extended thing.
Meaning: Can you picture yourself as JUST a mind alone? Without the body? IE: can you imagine yourself as a ghost floating through walls, occupying no physical space?
P2. I have a clear and distinct idea of my body as a non-thinking extended thing.
Meaning: Can you picture yourself as JUST a body alone? Without the mind? Essentially, can you imagine yourself as just a slab of meat?
C1. These opposing properties allow us to conceive of the mind separate to and without the body.
Meaning: If you're able to do the above 2 things, that means you have successfully separated the existence of the mind and the body, as two distinct entities that can exist without each other.
P3. What is conceivably separate is possibly separate.
Meaning: Like bullet point 1 says on the other side - If two things are actually identical, then they cannot possibly be separate because the separability of two identical things cannot even be thought about.
P4. What is possibly separate is actually non-identical.
Meaning: Same as above, just written the other way around.
C2. Therefore, the mind and body are not identical.

The Conceivability Argument

If two things are actually identical, then they cannot possibly be separate because the separability of two identical things cannot even be thought about.
E.g. we cannot conceive of a triangle without three sides. Because three sidedness and triangles are identical.
So, Descartes has set the criteria for things being identical which is inseparability.
P1. I have a clear and distinct idea of myself as a thinking non-extended thing.
P2. I have a clear and distinct idea of my body as a non-thinking extended thing.
C1. These opposing properties allow us to conceive of the mind separate to and without the body.
P3. What is conceivably separate is possibly separate.
P4. What is possibly separate is actually non-identical.
C2. Therefore, the mind and body are not identical.

We can conceive of the mind without the body and we can conceive of the body without the mind. This means they are separable and thus non-identical.

Criticism: Masked Man Fallacy & Intensionality

Masked man fallacy: Arguments that infer real-world possibilities from conceivability are susceptible to the masked man fallacy:

Imagine you heard about a masked man robbing a bank.
You believe that it is not your father.
However when the mask is removed from the man, it really IS your father.
Therefore, differences in what you know or can conceive do not guarantee differences in reality.
The mistake here was assuming that because you did not know it was your father, he must be someone else. Differences in what you know or can conceive do not guarantee differences in reality.
This is a problem with something called intensionality. Intensionality is when the truth of a statement depends on someone’s beliefs, knowledge, doubts, or perspective, rather than on objective facts. It is not necessarily wrong, but it becomes incorrect when you use these types of statements to imply a fact about reality.
This is what Descartes is doing. He observes that he can conceive of his mind existing without his body but cannot conceive of his body existing without his mind. From this, he concludes that mind and body are distinct substances.
Descartes has used two perspectives and beliefs to establish a metaphysical difference between mind and body which not logically justified.

Criticism: The Interaction Problem

This is a criticism of interacationalist dualism in general, so you would use this criticism in an essay to attack the dualist's claim that the mental and physical interact with each other.
How can a non-physical mind interact with a physical body? If you touch a hot pan which causes the mental feeling of pain, that seemingly causes the physical reaction of pulling the hand away. This requires a non-physical mental substance to causally affect and interact with physical substance.
Princess Elisabeth of Bohemia argued that genuine interaction requires a shared physical nature: only physical things can push or act on other physical things. A non-physical mind cannot generate a force. Therefore, if the mind is non-physical, it cannot physically interact with the body.
However, given that the mental can seemingly cause the physical like in the example above it seems that there is a causal relationship which means that the mental physically exerts some sort of force. Therefore, dualism is false.

PE34_Portrait_Elisabeth_as_Diana_Gerard-van-Honthorst_w1630c_LOW_RES.jpg

Criticism: The Category Mistake

Descartes says that physical objects are extended, space occupying things. He then argues that the mind is non-extended and thinking. So, the mind is not a physical thing and must therefore be a non-physical thing.
Gilbert Ryle argues that just because the mind is not a physical thing, that doesn’t mean it must be a non-physical thing. It is not a thing at all.
Descartes incorrectly puts the 'mind' in a category where it does not belong, the category of "thing". This would be like putting "yellow" in the category of "smells".
Ryle is a behaviourist and says that what we mean by "mind" actually refers to sets of behavioural dispositions.
“I shall often speak of it, with deliberate abusiveness, as “the dogma of the Ghost in the Machine“.