dualist theories
substance dualism → there are two kinds of substances: mental substances and physical substances
Descartes arguments for substance dualism
1) starting point
- either I receive sense perceptions from my body and other bodies themselves, so they exist, or some
higher being but the false idea in my mind
- God would not do this as he is not a deceiver and he would not allow another being to do so
- the mind is not in the body as a sailor is in a ship, instead there is intermingling between the mind and
the body
- you cannot separate your body from yourself - you are your mind, but your body has
emotions/appetites etc which are united with the mind
2) indivisibility argument
- my body is divisible → if you chopped your leg off, you would be dividing your body
- our bodies are extended in space - whatever is extended can have something taken away from
it
- my mind is not divisible → you cannot have half a thought
- our mind is not extended in space, it is a singular entity that cannot be divided into pairs
- therefore the mind and the body cannot be the same thing
- Leibniz’s Law → no two things can share all their properties in common
☒ objection → the mind is divisible
- multiple personality disorder
- left and right hemispheres of the brain severed
- corpus callosotomy → surgical procedure for epilepsy where the main connection (corpus
callosum) between the left and right hemispheres of the brain is severed
- not everything that is physical is divisible
- eg heat, running
☒ objection → masked man fallacy
- seems to based on Leibniz’s Law, but this does not apply when intentional states (eg knowing, being
aware) are introduced
- arguments switch from talking about his ideas of mind and body to the actual things themselves, but
this reasoning is fallacious
- eg I have an idea of Batman as a superhero and I have an idea of Bruce Wayne as a billionaire
who is not a superhero, therefore Batman is not Bruce Wayne
- Batman is Bruce Wayne, so the conclusion is false
3) conceivability argument
1. if I can clearly think of one thing apart from another thing, the two must
be distinct
2. I think of my mind as a thinking, unextended thing
3. I think of my body as an unthinking, extended thing
4. I can conceive of my mind as having been created separate from my
body
5. therefore my mind and body can exist separately from each other
☒ objection
- it is possible to conceive of things that do not exist, eg unicorns
- there are three categories of unreal things that people may try to conceive of
1. logically impossible → contradictory or against the laws of logic, eg a round square
2. metaphysically impossible → one that is not a contradiction but also not physically possibly in
any conceivable universe (not a way the world could have been)
, 3. physically impossible → something that does not exist but could have existed (there could have
been a world where unicorns existed)
- if the mind being separate from the body is more than a physical impossibility, that could give more of a
problem for Descartes’ argument
- the mind being separate from the body doesn’t seem to involve a contradiction, so whether
there is an inherent problem for Descartes seems to depend on there being a category of
metaphysical impossibility
- just because something is logically possible and metaphysically possible doesn’t mean it is
physically possible
problems with dualism
1) the problem of other minds
- solipsism → the idea that one’s own mind is the only thing that can be known to exist
- each of us only experiences our own thoughts, sensations and feelings
- even though we cannot experience others thoughts, we assume people have them
- however, if substance dualism is true, you cannot make this assumption
- if the mind and body are two independent substances, how do you know there is a mind
‘attached’ to a body?
- it is possible to have physical behaviour without a mind
- philosophical zombies
- Wittgenstein’s beetle in a box thought experiment
- everyone has a box with something in it, which is called a beetle
- no one can see into anyone elses box, but everyone says they know what a beetle is only by
looking at his beetle
- it is possible for everyone to have something different in their box, or not have anything in their
box at all
1. either mental state terms name something internal, which is private and inaccessible to others,
or they pick out something external which is public and accessible to others
2. if mental state terms pick out something internal which is private and inaccessible to others,
then it is possible that the internal experience each of us associates with a mental state term,
such as pain, is different from others
a. it is possible that we do not mean the same thing by the use of mental state terms
3. if mental state terms pick out something external which is public and accessible to others, then
it is possible for mental state terms to have some stable component of meaning in virtue of
which others can communicate with one another
4. so, mental state terms cannot only have a private component of meaning, in virtue of which
their meaning is exhausted
5. mental state terms also have a public meaning component
- Ryle’s university objection
1. a foreigner visiting Cambridge for the first time is shown a number of buildings, then asks
‘where is the University?’
2. it has to be explained that the University is not another institution, it is just the way in which he
has already seen is organised
3. he was mistakenly allocating the Uni to the same category as that to which the other institutions
belong
- category mistake → when a predicate is applied to a domain for which it is not defined
- eg, 2 has parents from Detroit - 2 refers to a number, and the property of having a
parent does not apply to the number 2
Ryle and arguments against the Official Doctrine
- according to Ryle, the official doctrine runs as follows
1) every human has both a mind and a body, with exception of infants and people in PVS
2) the body is public
, 3) the mind is private
- introspection is possible, but no one has direct access into the mind of another
- therefore, there is no reason to believe in the existence of other minds
☒ objection → Mill's argument from analogy
1. I have a mind
2. my mind causes my behaviour
3. other people have bodies and behave similarly to me in similar situations
4. by analogy, their behaviour has the same type of cause as my behaviour - a mind
5. therefore, other people have minds
☒ counter-response
- one example of a relationship between mind and behaviour is not sufficient to prove the
relationship holds in all cases
2) causal interaction → princess elisabeth of bohemia
- how can something that is immaterial act on something physical?
1. physical things only move if they are acted upon
2. only something that is physical and can touch the thing that is moved can exert such a force
3. the mind is not physical, so it can’t touch the body
4. therefore, the mind cannot move the body
- the conclusion is false, so the argument is false
- mainly an issue for interactionist dualism, not so much for epiphenomenal dualism
- interactionist dualism → the mind can interact with the physical world and the physical world
can interact with the mind
- eg, mental state of hunger causes you to go get food
- eg, getting hit in the head causes the mental state of pain
- epiphenomenalist dualism → the physical world can cause mental states, but mental states
cannot cause changes in the physical world
- me going to get food would be explained by my brain state, not my mental state
- epiphenomenalism is a subset of property dualism
substance dualism → there are two kinds of substances: mental substances and physical substances
Descartes arguments for substance dualism
1) starting point
- either I receive sense perceptions from my body and other bodies themselves, so they exist, or some
higher being but the false idea in my mind
- God would not do this as he is not a deceiver and he would not allow another being to do so
- the mind is not in the body as a sailor is in a ship, instead there is intermingling between the mind and
the body
- you cannot separate your body from yourself - you are your mind, but your body has
emotions/appetites etc which are united with the mind
2) indivisibility argument
- my body is divisible → if you chopped your leg off, you would be dividing your body
- our bodies are extended in space - whatever is extended can have something taken away from
it
- my mind is not divisible → you cannot have half a thought
- our mind is not extended in space, it is a singular entity that cannot be divided into pairs
- therefore the mind and the body cannot be the same thing
- Leibniz’s Law → no two things can share all their properties in common
☒ objection → the mind is divisible
- multiple personality disorder
- left and right hemispheres of the brain severed
- corpus callosotomy → surgical procedure for epilepsy where the main connection (corpus
callosum) between the left and right hemispheres of the brain is severed
- not everything that is physical is divisible
- eg heat, running
☒ objection → masked man fallacy
- seems to based on Leibniz’s Law, but this does not apply when intentional states (eg knowing, being
aware) are introduced
- arguments switch from talking about his ideas of mind and body to the actual things themselves, but
this reasoning is fallacious
- eg I have an idea of Batman as a superhero and I have an idea of Bruce Wayne as a billionaire
who is not a superhero, therefore Batman is not Bruce Wayne
- Batman is Bruce Wayne, so the conclusion is false
3) conceivability argument
1. if I can clearly think of one thing apart from another thing, the two must
be distinct
2. I think of my mind as a thinking, unextended thing
3. I think of my body as an unthinking, extended thing
4. I can conceive of my mind as having been created separate from my
body
5. therefore my mind and body can exist separately from each other
☒ objection
- it is possible to conceive of things that do not exist, eg unicorns
- there are three categories of unreal things that people may try to conceive of
1. logically impossible → contradictory or against the laws of logic, eg a round square
2. metaphysically impossible → one that is not a contradiction but also not physically possibly in
any conceivable universe (not a way the world could have been)
, 3. physically impossible → something that does not exist but could have existed (there could have
been a world where unicorns existed)
- if the mind being separate from the body is more than a physical impossibility, that could give more of a
problem for Descartes’ argument
- the mind being separate from the body doesn’t seem to involve a contradiction, so whether
there is an inherent problem for Descartes seems to depend on there being a category of
metaphysical impossibility
- just because something is logically possible and metaphysically possible doesn’t mean it is
physically possible
problems with dualism
1) the problem of other minds
- solipsism → the idea that one’s own mind is the only thing that can be known to exist
- each of us only experiences our own thoughts, sensations and feelings
- even though we cannot experience others thoughts, we assume people have them
- however, if substance dualism is true, you cannot make this assumption
- if the mind and body are two independent substances, how do you know there is a mind
‘attached’ to a body?
- it is possible to have physical behaviour without a mind
- philosophical zombies
- Wittgenstein’s beetle in a box thought experiment
- everyone has a box with something in it, which is called a beetle
- no one can see into anyone elses box, but everyone says they know what a beetle is only by
looking at his beetle
- it is possible for everyone to have something different in their box, or not have anything in their
box at all
1. either mental state terms name something internal, which is private and inaccessible to others,
or they pick out something external which is public and accessible to others
2. if mental state terms pick out something internal which is private and inaccessible to others,
then it is possible that the internal experience each of us associates with a mental state term,
such as pain, is different from others
a. it is possible that we do not mean the same thing by the use of mental state terms
3. if mental state terms pick out something external which is public and accessible to others, then
it is possible for mental state terms to have some stable component of meaning in virtue of
which others can communicate with one another
4. so, mental state terms cannot only have a private component of meaning, in virtue of which
their meaning is exhausted
5. mental state terms also have a public meaning component
- Ryle’s university objection
1. a foreigner visiting Cambridge for the first time is shown a number of buildings, then asks
‘where is the University?’
2. it has to be explained that the University is not another institution, it is just the way in which he
has already seen is organised
3. he was mistakenly allocating the Uni to the same category as that to which the other institutions
belong
- category mistake → when a predicate is applied to a domain for which it is not defined
- eg, 2 has parents from Detroit - 2 refers to a number, and the property of having a
parent does not apply to the number 2
Ryle and arguments against the Official Doctrine
- according to Ryle, the official doctrine runs as follows
1) every human has both a mind and a body, with exception of infants and people in PVS
2) the body is public
, 3) the mind is private
- introspection is possible, but no one has direct access into the mind of another
- therefore, there is no reason to believe in the existence of other minds
☒ objection → Mill's argument from analogy
1. I have a mind
2. my mind causes my behaviour
3. other people have bodies and behave similarly to me in similar situations
4. by analogy, their behaviour has the same type of cause as my behaviour - a mind
5. therefore, other people have minds
☒ counter-response
- one example of a relationship between mind and behaviour is not sufficient to prove the
relationship holds in all cases
2) causal interaction → princess elisabeth of bohemia
- how can something that is immaterial act on something physical?
1. physical things only move if they are acted upon
2. only something that is physical and can touch the thing that is moved can exert such a force
3. the mind is not physical, so it can’t touch the body
4. therefore, the mind cannot move the body
- the conclusion is false, so the argument is false
- mainly an issue for interactionist dualism, not so much for epiphenomenal dualism
- interactionist dualism → the mind can interact with the physical world and the physical world
can interact with the mind
- eg, mental state of hunger causes you to go get food
- eg, getting hit in the head causes the mental state of pain
- epiphenomenalist dualism → the physical world can cause mental states, but mental states
cannot cause changes in the physical world
- me going to get food would be explained by my brain state, not my mental state
- epiphenomenalism is a subset of property dualism
