PHYSICALISM: Type Identity Theory

resposne to zombie argument

- type identity theories would argue that pz are metaphysically impossible

- mental states are brain states in the same way water is h2o

- metaphysically impossible to have one without the other, in same way it is metaphysically impossible to have water withiut h2o

conceivability argument against type identity theory.
firstly anything can be concieved of as seperate. also if brain and mind were
indirectly suggesting that one is not thinking of anything, indirectly suggesting that brain and mind not

mental states without brain states are conc- so they are possible- so mental states are not brain satets- so type identity theory is false

multiple realisability - putnam

mental states cannot be reduced to brain states because mental states are mutiply realisable

- the same mental state can come from many different brain states

- if type identity theory is true silicon based aliens cannot have the same belief as humans that 'grass is green' as they have a brain made from silcon, different structure to humans that would make for a different perceptions

- if TID is true, then one cannot have the same mental states without having the same brain state

- dog and human can have the same mental states, can both be in pain

- but they do not have the same brain state, same brain structure

- therefore TID is false

how would a dualist cateogrise pain and c fibres compared to type identity theory

- c fibres and pain are two seperate subsatnces

- tid, they are the same physical substance but a different concept

mR objection

hypothetical and anatomical scenarios
P1: Each type of mental state is multiply realizable through more than one distinct type of physical state.

o P2: If each type of mental state is multiply realizable through more than one distinct type of physical state, then it cannot be identical to any specific type of physical state.


o C1: Therefore, no type of mental state is identical to any specific type of physical state.

o P3: According to type identity theory, each type of mental state is identical to a specific type of physical state.

o C2: Therefore, type identity theory is false.

type identity theory

mental states can ontologically reduce to statements about physical properties, mental states are the same as brain states, but are not synonmous with brain states,

statements about mental states do not analytically reduce statements about brain states - mental properties are not equivalent in meaning to statements about mental states

- mind is the brain
- mental states are brain states
- pain is c fibers firing

mental states only appear different from physical states/ pain only appears different from c fibres firing because, one experiences former directly, yet one only knows of the latter indirectly, via science, observation etc

ontological reduction/ contingent identity - JCC Smart

mental states and brain states are contingently identical

- mental states ontologically reduce to brain states

- not correlations they are the same thing like h2o is the same as water

- but not analytic reductions since a denial would not result in contradiction

- pain can ontologically reduce to c fibres firing

- this is an a posterior, empirical discovery

ockham razor (can also be argument against dualism) - dualism is made too complex

"do not multiply entities beyond necessity"

- do not make things more complex than they actually are
- out of two identical theories, the one that uses the fewest entities and the simpliest explanation is best

- type identity theory predicts the same things that dualism can but using one entity, the brain, rather than two, the mind and the brain

- should not posit extra entities to explain the mind when there is no overwhelming proof of dualism

- can explain as much about mental states by referring to the brain as one can gain by referring to a non physical mind

- eg when i feel pain= cfibres activated on scan, when c fibres activated, one feels pain suggesting they are the same thing, do not need to add anything else


dualist would say c fibres and pain are two seperate substances, type identity theory says they are the same physical thing but different concepts

location problem response - TID misjudges, makes sweeping claims by trying to focus so much on simplicity and an empirical explanation of mental states. shows how mental states cannot be emprically explained.

leibniz law of indiscernability of identicals

- brain state of c fibres firing has the property of having a physical location

- mental state of pain does not have the property of having a physical location

- cannot be the same thing if pain and c fibres are identical then they must share all the same properties

- c fibres have a precise physical location

- pain does not- therefore they are not identical

response to location problem smart

- merely a linguistic problem, sounds unfamiliar that one would attribute physical location to mental properties. just because it is unfamilar does not show that they do not have a physical location

- also begs the question
- to assume that mental states do not have a physical location is to assume that they are not brain states. this is false, pain does have precise location

begging the question

The situation that results when a writer or speaker constructs an argument on an assumption that the audience does not accept- assuming the truth of conclusion in premise

zombie argument against type identity theory

- can concieve of a philosophical zombie with brain state, c fibres firing but without experiencing pain

- concievable so they are possible

- mental states are not the same thing as brain states

response to the conc argument against type identity theory

(responses to conc argument) golook !

divisibility argument against type identity theory

brain is divisible, mind indivisible so mind and body are seperate substances

responses to the divisibility argument

go and look

contingently identical

mental states and brain states are contingently identical, mental states ontologically reduce to brain states

they are the same thing - water is h2o, pain and cfibres firing

why are ontological reductions not analytic reductions

- the opposite idea of an analytic reduction will result in a contradiction, an incohereny

- there is no logical contradiction mental states being the same as brain states

- so pain ontologically reduces to c fibres firing, but does not analytically reduce to it

which theory is most likely to be accepted according to ockham razor

the one which posits the fewest number of entities, the simplest one

- the simplest theory is the most accurate theory


- if there is no overwhelming proof for (dualism) then there is no need to posit any extra entities to explain the mind

how did jc smart reject dualism using ockham razor

type identity theory can predict everything that dualism can
- though type identity theory does so with one entity only, the brain

- rather than two entities as dualism does, the minds and the brain

- no overwhelming proof so should not just posit extra entities to explain the mind when mental states can be just as well explained using a physical explanation as a non physical one

according to the location problem, why are pain and c fibres not identical

pain does not have a precise phsyical location

- c fibres do have a precise physical location

- according to leibniz law, if two things are identical then they must share all the same physical properties

problems with tid

- location problem
- zombies
- concievability
- multiple realisability

how does multiple relisability reject type identity theory

- different brain states can produce the same mental state
- tid says that two entities cannot have the same mental state without having the same brain state
- but different brain states can produce the same mental state

- one can say that octopus have O fibres rather than c fibres, it is apt to say that they have have a different brain state to humans

- so if one was to stab an octopus, and were to watch it writhe around frantically, tid would say that this octpous is not experiencing pain

- but the octopus is experiening pain showing that te same mental states can be reliased by different brain sates,

- brain states are thus not identical to the mental states

cannot have the same mental state without having the same brain state

silicon based aliens multiple relisiability rejection

- a silicon based alien would not be able to form the belief that grass sis green if tid was true and only identical brain states can produce identical mental states

- the different strcuture of their brain would mean that they form different belief, not true (but how would we know, go sleep)