Phil - Substance Dualism

What is substance dualism?

A theory that there are two distinct substances, mental and physical. Mind and body are ontologically distinct.

What is the essence of physical substance and what is the essence of mental substance?

The essence of physical substance is extension

The essence of mental substance is thinking

Outline the conceivability argument

1. I clearly and distinctly think of my mind as being thinking and non-extended in space

2. I clearly and distinctly think of my body as being non-thinking and extended in space

3. Anything that I clearly and distinctly think of is metaphysically possible

4. Therefore, it is possible for my mind and body to be separate

5. If it is possible for my mind and body to exist separately, then they cannot be identical

6. Therefore, my mind is not identical to my physical body (or anything in the physical world)

Outline the indivisibility argument

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

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

3. 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.

List the responses to the indivisibility argument

• The mental is divisible in some sense

• Not everything thought of as physical is divisible

Explain the “the mental is divisible in some sense” response to the indivisibility argument

There are cases of mental illness in which the mind does seem literally divided. For example, someone with multiple personality disorder could be said to have a divided mind.

There are also examples of people having their brain damaged in accidents and reconstructed successfully

Explain the “not everything physical is clearly divisible” response to the indivisibility argument

If it’s possible to reach a point where physical matter becomes indivisible, then not everything that is indivisible is non-physical

And so, even if Descartes successfully shows that the mind is indivisible, this doesn’t prove that the mind is non-physical

It’s possible that the mind is the same kind of substance as the body (i.e. a physical substance) – it’s just an indivisible form of that same substance.

Explain a response to the “the mental is divisible in some sense” response to the indivisibility argument

These examples represent fragmentation or compartmentalization of mental activities, not the literal divisibility of the mind as a substance. Descartes did not deny that the mind has multiple faculties or functions, such as imagination, will, and intellect, but he maintained that these are unified within a single, indivisible substance.

Explain a response to the “not everything physical is clearly divisible” response to the indivisibility argument

Subatomic particles still possess spatial extension (e.g., a defined position or probability field in space-time) and exist within the framework of physical laws.

The mind, on the other hand, lacks spatial extension entirely. Its indivisibility is not just about the impossibility of physical division but about its fundamentally different mode of existence. For Descartes, the mind’s lack of spatiality is key to its distinction from all physical things, divisible or not.

List the responses to the conceivability argument

• Separating the mind and body is inconceivable

• What is conceivable may not be possible

• What is metaphysically possible tells us nothing about reality

Explain the “separating the mind and body is inconceivable” response to the conceivability argument

• Neuroscience demonstrates that mental activities are fundamentally tied to brain processes

• Without a functioning brain or body, the idea of a mind loses coherence because mental processes require physical substrates

Explain the “what is conceivable may not be possible” response to the conceivability argument

“Masked man fallacy”

Imagine Lois Lane has a clear and distinct idea of Clark Kent and superman as two different people. However, they are not, and it would be impossible for them to be

Explain the “What is metaphysically possible tells us nothing about reality” response to the conceivability argument

You cannot move from a priori reasoning to empirical facts

For example, it is possible for unicorns to exist but not physically true

In the same way, it may be possible for the mind and body to be separate, but that doesn’t make it reality

Explain a response to the “separating the mind and body is inconceivable” response to the conceivability argument

Descartes could respond that even if mental processes correlate with physical brain activity, this doesn’t undermine the possibility that the mind can exist independently. Correlation does not entail identity

Explain a response to the “what is conceivable may not be possible” response to the conceivability argument

Lois Lane doesn't have a clear idea of Clark Kent or Superman, nor is her idea of them necessarily distinct. It is, however, a clear and distinct idea for her (if she thought about it) that they are the same person, so it possible (and also happens to be true).

Explain a response to the “what is metaphysically possible tells us nothing about reality” response to the conceivability argument

Although it is true for everyday concepts, Descartes is asking about the very identity of two things, and if they COULD even be the same. As they cannot be identical, they must be separate.

If they were identical, what would you be separating? Something from itself?