DUALIST THEORIES: Substance Dualism

substance dualism

- minds exist and are not identical or part of bodies

- there are non physical substances in addition to physical substances

- mind and body are different substances

- body is extended physical substance, whereas the mind is an unextended non physical substance

Concievability Argument (apriori deductive)

1) i have a clear and distinct idea of my mind as a thinking thing that is not extended in space

2) i have a clear and distinct idea of my body as a non thinking thing that is extended in space

3) anything that i can conceive of clearly and distinctly is something god could create / is metaphysically possible

4) it is metaphysically possible that mind exists without a physical body

5)so it is possible for mind and body to exist independently

6) so mind ad body are two seperate substances

4th implied premise of divisibility argument - Leibniz law of indiscernibility of identicals

-if two things are the same thing then they will have the same properties
- two things have different properties then they cannot be the same thing

divisibility argument - mind is divisible in certain ways

- multiple personality disorder, parts of the mind appear separate to the other, different memories, beliefs, personality traits, often unaware that the other part exists


- split brain surgery, severed corpus collosum in corpous callostomy to seperate left and right hemispheres of brain, side effects including personality changes which could be the mind being divided

divisibility argument - response to mind being divisible in certain ways

- mind not divisible in the same way the body is divisible

- multiple personalities and split brain examples of mind being functionally divisible

- physical body is spatially divisible, can cut off finger and move it to another location in space

still means that mind can be a non physical substance that is separate from the body

divisibility argument - not everything is physically divisible

- even if mind is indivisible this does not prove that it is a separate substance from the body, mind could be an indivisible physical substance

- could be a point in which physical substances stop becoming divisible, arm - atoms - subatomic atoms - becoming an indivisible physical substance

means even if the mind is an indivisible substance, this does not prove that it is a non physical substance, as physical substances, may also reach a point of indivisibility

what does conceivability argument rely on

- anything one has a clear and distinct idea of is something which can be created by God in a way that alligns with this idea

- God is omnipotent hence the only time He would not be able to create something is if they are contradictory. the concepts of mind and body are not contradictory

- hence, God has created mind as non physical substance not extended in space, and body as a physical substance that is extended in space (possible that they exist as independently and are separate substances)

response to conceivability argument - mind without body is inconceivable

behaviourism - all that is mental is firstly physical, all mental states are behavioural dispositions, mind and body inorexiably linked

impossible to have mind without body since it is the equivalent of saying that means to have behavioural dispositions without behavioural dispositions (contradiction) and contradictions are inconceivable

- to have mental states is to have behavioural dispositions
- to have behavioural dispositions is to be disposed to move body in certain ways
- inconcievable to move body in certain ways without having a body
- incon to have mental states without body
- hence mind without body incon

response to mind without body not concievable

assuming behaviourism is correct account of the mind. if it is wrong then there is no contradiction in the idea of mental states without behavioural dispositions

what is conceivable may not be possible - conc argument , masked man fallacy

- challenges descartes inference that mind without body is concievable to conclusion that mind exists without body

- concieve of batman as caped crusader
- conceive of bruce wayne as a billionaire who is not a caped crusader
- therefore batman is not bruce wayne

(impossible for batman to be anyone else other than bruce even though it is concievable)

- descartes argument switches from talking about ideas to things themselves. ideas of what is possible can be mistaken, and not possible

just because one has idea of mind and body being seperate things , does not mean that it is possible they are

response to the masked man fallacy

- likely accept that one cannot always infer ideas to reality

- though the ideas in masked man fallacy were not clear and distinct

- clear and distinct idea is one where the truth can be seen through rational intuition

- 'my mind is a thinking thing that is not extended in space' reveals it is true, whereas the masked man fallacy, the truth of the proposition cannot be seen

what is possible tells us nothing about the actual world - conceivability argument

- even if it is possible that mind without body can exist, does not inform anything about reality since there are logically possible things that can occur in reality that are physically impossible to do. only logically possible since there is no contradiction

- logically possible to jump to moon, but physically it is impossible

- it is possible that mind and body are separate substances, but this doesn't show they are separate substances in reality. it is equally possible that mind and body are the same substance


argument is theoretical, arguing mind and body separate, overall theoretical debate - mind is invisible, unable to be studied. useless to debate

problem of other minds

- since sd claims mind and body are separate substances, physical behaviour without mind can exist
- impossible to know if other minds exist if substance dualism is true

Mill response to problem of other minds, analogy

- i have a mind and mind causes behaviour
- other people have bodies and behave in a similar way to me in similar situations
- by analogy, mind also causes their behaviour
- therefore other people have minds

solisism response to mill argument from analogy

- only one example of relationship between mind and behaviour is insufficient to suggest the relationship holds in all cases
- one instance of something cannot be generalised to all instances

problem of other minds response - other minds are the best hypothesis

- still reasonable to believe that other minds exist even if one cannot prove
- like science, if other people had minds it would adequetely explain behaviour
- minds - similar theoretical entities studied in science

descartes response to the conceptual interaction problem

'passions of the soul' scientific explanation , by willing something the 'little gland' closely joined will move (pineal) to create corresponding response

does not explain how the act of willing/ action of non physical mind causes the gland to move

version 2 - empirical interaction problem

law of conservation of energy states that in a closed system energy cannot be added or removed only transferred
- universe is a closed system
- if sd is true energy is always added in closed system each time one thinks
- if sd is true, law of ocnservation of energy is false
- more loc evidence, means sd must be false

arguments for substance dualism

- conceivability argument
- divisibility argument

arguments against substance dualism

- interaction problem
- problem of other minds

the divisibility argument (descartes)

1) my body is a divisible substance
2) my mind is an indivisible substance
3) therefore my mind and body are separate substances, they cannot be the same thing

causal interaction - conceptual interaction, version 1

- how can mental things interact with physical things when they are supposed to be different substances

- physical things can only move when they are pushed

- only something that is physical and can touch the thing that is moved can push it
- if substance dualism is true then mind is non physical and cannot touch the body
- is sd is false mind cannot move the body
- mind can move the body so sd is false

how does descartes concievability argument fail

- switches from talking about ideas of things, ideas that mind and body are separate, to concluding that this is how they are in themself
-

how does divisibility argument fail

divisibility is not an indiciator of whether a substance is physical or non physical
- can have a non divisible physical substance, subatomic

3rd premise of conc argument

3) anything i have a clear and distinct idea of is something god created
(- so god created my mind as a non physical thinking thing not extended in space and body as a non thinking physical thing that is extended in space)

+ one has no experience with non physical causality. causation = physical concept. mind complexity and uniqueness = exempt, beyond comprehension.

may seem implausible, since human rationalise, comprehnd things based on physical evidence.
- causation + effect = a concept attributed to all physical properties, since the idea was derived from observation of physical things
- could say a fallacy of compositon of sorts in attributing this notion of physical causation, and demaning that it also applies to non physical mind.
= mind is non physical, whatever causal affects it has = different, can only be incomprhensible


- to eliminate idea of mind simply cause it does not have phsyical origin is to devalue the complexity and uniqueness of the mind and consciousness.

features of mental states

- all or some mental states have phenomenal properties
- (Some) referred to as qualia, intrinsic and non intentional phenomenal properties that are introspectively accessible
- all or some mental states have intentional properties (intentionality)