Dualist theories

Define Substance dualism

Minds exist and are distinct from bodies and parts of bodies. They are ontologically separate from one another - made of different substances with different properties

Outline the indivisibility argument

Descartes’ individisbility argument is an argument in favour of substance dualism: it attempts to establish that Minds and bodies are ontologically disitinct substances.

P1) Physical substance can be divided (I can conceive of it being so)

P2) Mental substance cannot be divided (I cannot conceive of it being so)

P3) Two things are identical iff. they have the same properties (Leibniz’s law of indiscernables)

C)Mental and physical substance have distinct properties, so they are distinct substances

Responses to the indivisibility argument

Physical substance may not be divisible: electric fields?

Mental substance may be divisible: splitting of brain hemispheres? the subconsconsiocus?

Counter-repsponses to the indivisibility argument

Electric fields arent extended nor substance - they are a helpful abstraction

It may be the case that the work of the brain is impaired in these cases but moment-to-moment one thing is being thought

Outline the conceivability argument

The conceivability argument defends substance dualism: the position that mental and physical are ontologically distinct substances.

P1) I can conceive of my mind existing without my extended physical body (and without any physical world) (logical possibility)

p2) Anything I can clearly and distinctly conceive of is metaphysically possible(as God could make it so)

C) So my mind existing distinct from my body is metaphysically possible

P3) If it is metaphysically possible for the X to exist without Y then X and Y are not identical

C) so mind and body are not identical

Responses to p1 of the the conceivability argument

Is mind without body conceivable?

Hume argues no - the mind is a clump of sense impressions and the derived ideas, and so they cannot be meaningfully separated

•To talk about beliefs, desires, choices, etc is to talk about how something behaves. 

•However, without a body, we cannot exhibit behaviour. 

•And without behaviour, there is no mind. 

•Therefore, it is not possible that mind exist without body (this would be a "ghost in the machine")

•Therefore, it is not conceivable that mind exist without body. 

Descartes’ response to refutation of conceivability of mind distinct from bosy

•If mind without body is not conceivable, then What happens to God? 

•Aredisembodied minds, such as God, are inconceivable?

•However, we do have a concept of God

• Therefore, mind without body is conceivable.

•However, in the case of clear and distinct ideas, we can’t make mistakes.

•I can clearly and distinctly that my mind is separate from my body, so it must be so.

Respomses to P2 of the conceuvabilitty argument

Logical possibility and metaphysically possibility don’t necessarily follow: water and H2O are logically distinct, but not metaphysically so

Descartes commits a masked man fallacy: my mind is thinking and my body is unthinking, so they must be separate in reality as they are in my conception.

They could be properties of the same substance

Descarte’s defence of P2 of the conceiveablility argument

We can only accept logical → metaphysical possibility in the case of clear and distinct ideas

Challenge to P3 OF THE CONCEIVABILITY ARGUMENT

Metaphysical possibility of difference doesnt entail distnction in reality - because it is also metaphysically possible that they could be the same.

Thus we cannot conclude that metaphysical possibility is sufficient for reality to reflect it

Descartes’ defence of P3 of the conceivability argument

•It is metaphysically impossible for mind and body to be the same substance as they have opposite properties.

•Mind and body do interact, which explains why there is a connection between mental states and brain states.

Interactionist dualism claims

Mental states are non physical

What happens physically causes what happens mentally

What happens mentally causes what happens physically

The conceptual problem of interactionist dualism

causation without contact/ energy transfer is inconceivable

If something is inconceivable it is likely impossible

Causation between the physical and non physical could not possibly involve contact/energy transfer

Causation between physical and non physical is likely impossible

Descartes response to the conceptual problem

Explain the empirical problem facing interactionist dualism

P1) The universe is a close causal system in which the total amount of energy remains constant

P2) Any nonphysical to physical causation would have to involve an addition of energy to the physical world

P3) Any physical to nonphysical causation would have to involve a loss of energy from the physical world

C) Therefore non-physical to physical causation is not empirically possible

Occum’s razor makes this a better theory