Exam Board Checklist for Substance Dualism 

The mind–body problem: What is the relationship between the mental and the physical?
​
Dualism: the mind is distinct from the physical
The indivisibility argument for substance dualism (Descartes)
Issues, including: the mental is divisible in some sense, not everything thought of as physical is divisible.
The conceivability argument for substance dualism: the logical possibility of mental substance existing without the physical (Descartes).
Issues, including: mind without body is not conceivable, what is conceivable may not be possible, what is logically possible tells us nothing about reality

What is Substance Dualism?

There are two fundamentally different types of substances:

• Physical (or material) substances e.g. bodies and physical objects - Descartes calls this res extensa
• Mental substances or minds - Descartes calls this res cogitans 

​Minds do not depend on bodies in order to exist, they can exist separated from any body.
​Minds and bodies are ontologically distinct and independent. 

Rene Descartes

(1596 – 1650)

The Conceivability Argument

• I have a clear and distinct idea of myself as something that thinks and isn’t extended
• I have a clear and distinct idea of body as something that is extended and does not think
• If I have a clear and distinct thought of something, God can create it in a way that corresponds to my thought
• Therefore, God can create mind as something that thinks and isn’t extended and body as something that is extended and does not think
• Therefore, mind and bod can exist independently of one another
• Therefore mind and body are two distinct substances

The Cogito 
Descartes argued that his true self can be identified with his consciousness or mind; that his essential nature is thought. I, as he says, am a ‘thinking thing’ and it is conceivable that this thing might exist without a physical body.
Reliance on God?
The argument does not rely on God's existence. Rather Descartes uses the idea of God as a way of talking about what is logically possible. Whatever is clearly conceivable is possible, since God is omnipotent he could make it so. 

The Indivisibility Argument

• My mind is indivisible
• My body is divisible
• My mind is not my body

​
Leibniz’s Law – Identity (sameness) of Indiscernibles
If you think you have two things and they have all the same properties including their position in space then they are identical. 

If X and Y do not have all the same essential properties they cannot be the same kind of thing (X cannot = Y)
​

• If two things share all the same properties, they must be one thing.
• If one has any property that the other lacks, they must be distinct.
• Divisibility is a property of bodies that minds lack
• Minds must be different from bodies 

​Exam Board Checklist for Property Dualism 

​The ‘philosophical zombies’ argument for property dualism: the logical possibility of a physical duplicate of this world but without consciousness/qualia (Chalmers).
Issues, including: a ‘zombie’ world is not conceivable, what is conceivable is not possible, what is logically possible tells us nothing about reality.
The ‘knowledge’/Mary argument for property dualism based on qualia (Frank Jackson).
Qualia as introspectively accessible subjective/phenomenal features of mental states (the properties of ‘what it is like’ to undergo the mental state in question) – for many qualia would be defined as the intrinsic/non-representational properties of mental states.
Issues, including: Mary gains no new propositional knowledge (but gains acquaintance knowledge or ability knowledge), all physical knowledge would include knowledge of qualia, there is more than one way of knowing the same physical fact, qualia (as defined) do not exist and so Mary gains no propositional knowledge.