dualism

Question 1

what is substance dualism

Answer 1

Substance dualism says there are two completely different kinds of substance in our universe:

Mental substances
Physical substances
Physical substances are things like the trees, cars, houses, etc. Your body – your arms, legs, etc. – is a physical thing as well.

The brain is part of the body, hence it is also physical. But dualists deny that the mind is the same thing as the brain. Instead, dualists argue that the mind is something completely different to the brain – something non-physical.

Most people who believe in souls are dualists. Typically, the soul isn’t thought of as a physical thing – you can’t touch it, or see it, for example. Similarly, things like ghosts and angels are somewhat dualist – they’re not thought to be made of physical stuff.

Question 2

descartes conceivability argument

Answer 2

Descartes’ conceivability argument can be summarised as:

I have a clear and distinct idea of my mind as a thinking thing that is not extended in space
I have a clear and distinct idea of my body as a non-thinking thing that is extended in space
Anything I can conceive of clearly and distinctly is something that God could create
So, God could create my mind as a thinking thing that is not extended in space and my body as a non-thinking thing that is extended in space
So, it is possible for mind and body to exist independent of each other
So, mind and body are two separate substances
In other words, Descartes is saying that it is conceivable – and therefore possible – for mind and body to exist separately. He then takes this to show that mind and body are separate things.

Note: It may seem a bit of a leap from it’s possible that mind and body are separate to mind and body are separate in reality. Descartes’ argument for this inference is heavily reliant on his notion of clear and distinct ideas. Clear and distinct ideas are trustworthy, complete, and true rather than just random thoughts that may or may not be accurate.

Question 3

response to conceivability mind without body is inconceivable

Answer 3

Behaviourism says that to have mental states is to have behavioural dispositions
To have behavioural dispositions is to be disposed to move your body in certain ways
It is inconceivable to be disposed to move your body in certain ways if you don’t have a body
So, it is inconceivable to have mental states if you don’t have a body
So, mind without body is inconceivable

Question 4

against conceivability what is conceivable may not be logically possible

Answer 4

Just because we can imagine the mind floating around independently of a body, this doesn’t mean it is physically possible. It might be logically possible – i.e. it doesn’t involve a logical contradiction – but just because something is logically possible, this doesn’t mean it is physically possible!

For example: it is not logically possible for a triangle to have 4 sides because it involves a logical contradiction.

But it is logically possible for me to jump on to the moon from earth. It might be physically impossible, but there is no logical contradiction in this idea!

Similarly, just because it’s conceivable/logically possible for a mind to exist independently of a body, this doesn’t automatically mean such a thing is physically possible.

Question 5

masked man fallacy response to conceivability

Answer 5

Another response to the conceivability argument attacks Descartes’ inference from the claim that mind without body is conceivable to the conclusion that mind exists without body in reality. The fallibility of this inference can be shown with the following example:

I conceive of Batman as a caped crusader
I conceive of Bruce Wayne as a billionaire who is not a caped crusader
Therefore, Batman is not Bruce Wayne
If you know the Batman story, Batman is Bruce Wayne’s secret identity. So the conclusion is clearly false: Batman is Bruce Wayne.

So, even though it may be conceivable that Batman is someone else, this tells us nothing about how things are in reality. To think otherwise is to fall for the masked man fallacy.

masked man fallacy
Just because it’s conceivable that these are two separate people, it doesn’t necessarily mean they are two separate people in reality
The reason this argument is fallacious is because it switches from talking about ideas to talking about things themselves. But, like the Batman example, sometimes our ideas are mistaken and reality is different from our idea of it. We can argue that Descartes’ conceivability argument makes the same mistake as the Batman example:

Just because you have an idea of Batman and Bruce Wayne as separate people, this doesn’t mean they are separate people
Similarly, just because you have an idea that the mind and body are separate things, this doesn’t necessarily mean they are separate things

Question 6

descartes divisibilty

Answer 6

Descartes’ divisibility argument can be summarised as:

My body is divisible
My mind is not divisible
Therefore, my mind and body are separate things
(This argument makes use of Leibniz’s law of identicals, which says that for A and B to be the same thing, A and B must have all the same properties. If two things have different properties, they cannot be the same thing).

The first premise is definitely true. If you chopped you leg or your arm off, you would be dividing up your body.

The mind, however, does not seem divisible – at least not in the same way. You can’t, for example, have half a thought.

Question 7

response - the mind is divisible

Answer 7

There are cases of mental illness in which the mind does seem literally divided. For example, someone with multiple personality disorder could be said to have a divided mind.

Another example of this would be people who have literally had their brain cut in half. A corpus callosotomy is a surgical procedure for epilepsy where the main connection between the left and right hemispheres of the brain is severed. Perhaps surprisingly, patients go on to live perfectly normal lives – although there can be a few weird side effects:

Question 8

not everything physical is divisble

Answer 8

We can also respond by arguing that even if the mind is indivisible, this doesn’t necessarily prove Descartes’ conclusion that the mind is a separate kind of substance. Instead, it’s possible that the mind is just an indivisible type of physical substance.

Obviously, you can divide the physical body: The examples above of cutting off a leg or an arm show this. But if you keep dividing it, you might eventually reach a point where you cannot divide it any further. Eventually, for example, you’ll just be left with a load of atoms, and perhaps those atoms could be divided into sub-atomic particles, but eventually you might reach a form of physical substance that is indivisible (units of energy, say, or whatever physics says – the specifics don’t really matter). The point is this:

If it’s possible to reach a point where physical matter becomes indivisible, then not everything that is indivisible is non-physical
And so, even if Descartes successfully shows that the mind is indivisible, this doesn’t prove that the mind is non-physical
It’s possible that the mind is the same kind of substance as the body (i.e. a physical substance) – it’s just an indivisible form of that same substance.

Question 9

problems for substance dualism- other minds

Answer 9

Each of us only ever experiences our own thoughts, sensations, feelings, etc. We might empathise when we see someone hurt themselves but we don’t literally feel their pain. If we both look at the same sunset we are looking at the same thing but each of us is having a different, private, experience in our mind.

Yet even though you might never literally experience my thoughts, you’d still assume I have them (except maybe in weird philosophical contexts like this one). You don’t seriously doubt whether your friends, family, and random people on the street have minds. You infer from their behaviour that they have a mind that causes their behaviour.

But if substance dualism is true, what grounds do you have to make this assumption? Minds and bodies are two completely separate and independent substances. How do you know there is a mind ‘attached’ to a body? It’s completely possible, on the dualist view, to have physical behaviour without a physical mind. In such a case, what evidence could you possibly find which proves other minds exist at all? It seems substance dualism leads to scepticism about the existence of other people’s minds.

Question 10

response to other minds

Answer 10

John Stuart Mill responds to the problem of other minds by drawing an analogy between his own mind and the minds of others:

I have a mind
My mind causes my behaviour
Other people have bodies and behave similarly to me in similar situations
By analogy, their behaviour has the same type of cause as my behaviour: a mind
Therefore, other people have minds
However, the problem of other minds can respond that one example of a relationship between mind and behaviour (my own) is not sufficient to prove the relationship holds in all cases. It would be like saying “that dog has 3 legs, therefore all dogs have 3 legs.”

It’s a dubious inference to go from one instance of a relationship (I have a mind that causes my behaviour) to the claim that this relationship holds in all instances (everyone has a mind that causes their behaviour).

Possible response #2: Other minds are the best explanation

Another response to the problem of other minds accepts that we can’t observe or prove the existence of minds, but says we should believe in their existence anyway since they are the best explanation (i.e. an abductive argument).

One way you could argue other minds are the best explanation is their explanatory and predictive power: If other people have minds, it explains why they behave in the ways they do. For example, if someone spends a few minutes before moving a chess piece in a chess match, the best explanation of their behaviour is that they have a mind and were using it to think through their move before making it.

Question 11

causal interaction problem for dualism

Answer 11

Another issue for substance dualism is how mental things can causally interact with physical things when they are supposed to be two completely separate substances.

Our mental states affect how we behave. If I’m feeling hungry (mental state), it might cause me to move my body (physical thing) to the fridge to get some food.

But if the mental state is non-physical, how does it transfer over into the physical world and cause things to happen?

Question 12

property dualism

Answer 12

the view that there is just one kind of substance and two fundamentally different types of property - mental and physical

Question 13

qualia

Answer 13

n plain English, qualia are the subjective properties of experience – i.e. what something feels like inside. Examples of qualia include:

The redness I experience when I look at a ripe tomato
The taste of beer when I have a drink
The rough feeling when I run my hand over some sandpaper
Notice how qualia are not properties of the objects – i.e. properties of the tomato, or the beer, or the sandpaper – they are properties of experience of those objects.

Question 14

phenomenal knowledge

Answer 14

knowledge of what it is like to have a certain experience

Question 15

supervenience

Answer 15

Supervenience is a relationship between two kinds of thing. If something supervenes on something else, then it is dependent on that thing.

In metaphysics of mind, physicalism says that everything – including the mind and mental states – is either physical or supervenes on the physical. In other words, physicalism says that two physically identical things must be the same in every way: it’s impossible for two physically identical things to be mentally different.

Property dualism denies this claim, however. According to property dualism, it’s possible for two physically identical things to be different in some way. More specifically, property dualism says it’s possible that two physically identical things could have different mental properties – different qualia.

So, according to property dualism, qualia are neither physical nor supervene on the physical.

Question 16

interactionalism and epiphenomenalism

Answer 16

It’s worth introducing another distinction here, between epiphenomenalist and interactionist dualism:

Interactionist dualism: the mind can interact with the physical world and the physical world can interact with the mind. In other words, the mental and physical can interact in both directions.
Mental -> physical: The mental state of hunger causes you to go and get food
Physical -> mental: 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 – i.e. the causal interaction is one way.
Physical -> mental: Getting hit in the head causes the mental state of pain
But mental states (i.e. qualia) themselves don’t cause anything: My going to get food is explained by my (physical) brain state, rather than my mental state

Question 17

chalmers the zombie argument

Answer 17

A philosophical zombie is a person who is physically and functionally identical to an ordinary human – except they don’t have any qualia.

philosophical zombie argument for property dualism
The philosophical zombie (right) behaves and is physically identical to a normal human (left), except it doesn’t have qualia
A zombie will say “ouch!” when it gets stabbed and its physical brain will even fire in the same way as a normal brain – but there isn’t any pain qualia internally.

Such zombies seem conceivable. We can imagine a possible world that is physically identical to this one, with the same people, but without qualia. In this world, you would behave and act in exactly the same way as in the actual world except you’d have no phenomenal experience.

We can use this intuition to form an argument for property dualism similar to Descartes’ conceivability argument:

Philosophical zombies are conceivable
If philosophical zombies are conceivable then philosophical zombies are metaphysically possible
If philosophical zombies are metaphysically possible then qualia are non-physical
If qualia are non-physical then property dualism is true
Therefore, property dualism is true

Question 18

response to zombie argument- not conceivable

Answer 18

Physicalists can respond that if we had enough physical knowledge we would be able to understand what we currently call ‘qualia’ in purely physical terms. In other words, the only reason zombies seem conceivable is because we are confused or missing some important information. The conceivability of a physical duplicate without qualia is just an illusion – albeit a very powerful one.

The reason zombies seem conceivable is because we’re labouring under a false illusion that qualia are these spooky non-physical things. Once we understand that qualia are, in fact, just physical things, then it becomes inconceivable to imagine a physically identical being that lacks these physical features. Imagining a philosophical zombie would be like saying “imagine something that is physically identical but that isn’t physically identical” – it would be a contradiction, and contradictions aren’t conceivable. It would be like trying to imagine a married bachelor or a triangle with 4 sides.

Once we understand that qualia = a physical thing, it becomes inconceivable for two physically identical beings not to have identical qualia, and so the zombie argument fails to prove property dualism.

Question 19

Zombies are not (metaphysically) possible

Answer 19

We’ve already seen how logical possibility does not guarantee physical possibility. But we can introduce a third kind of possibility – metaphysical possibility – and respond to the zombie argument by arguing that conceivability does not guarantee metaphysical possibility.

Logical, Physical, and Metaphysical Possibility

It seems conceivable, for example, that water could be something other than H2O because a statement like “water is H3O” is not obviously contradictory in the same way “a triangle has 4-sides” is contradictory.

“Water is H2O” is not an analytic truth and so it seems that we can imagine water without imagining something with the chemical structure H2O. In contrast, we cannot imagine a triangle without imagining a 3-sided shape because “triangles have 3 sides” is an analytic truth. The apparent conceivability of “water is H3O” suggests such a thing is somehow possible.

However, some philosophers would reject that “water is H3O” is possible because H2O is an essential property of what water is. Sure, you can imagine a possible world where the clear liquid in lakes and rivers is H3O, but then what you’d be imagining wouldn’t be water! It would be something else. “Water is H3O” is thus metaphysically impossible.

Similarly, if phenomenal properties (qualia) are essential properties of some physical things, then it’s not metaphysically possible for the same physical thing to have different phenomenal properties. In other words, a physical duplicate without qualia (i.e. a philosophical zombie) is metaphysically impossible in the same way water without H2O is metaphysically impossible

Question 20

frank jackson- knowlege argument

Answer 20

Mary knows all the physical facts about colour
Mary does not know what it feels like to see colour
Therefore, what it feels like to see colour is not a physical fact
Physicalism says that all facts are physical facts
Therefore, physicalism is false

Question 21

response to the knowledge argument

Answer 21

Remember from epistemology the three kinds of knowledge:

Ability: knowledge how – e.g. “I know how to ride a bike”
Acquaintance: knowledge of – e.g. “I know Fred well”
Propositional: knowledge that – e.g. “I know that London is the capital of England”
We can accept that Mary learns something new when she leaves the black and white room but reject Jackson’s claim that this new knowledge is non-physical.

Instead, we might argue, Mary gains new ability knowledge.

There is nothing spooky or non-physical about knowing how to ride a bike. The fact that people are able to ride bicycles is not used as an argument against physicalism.

And we can imagine a similar case to the Mary example. However, this time, Mary learns all the physical facts about riding a bicycle (and all the related causal and relational facts) from books and videos, etc. without ever actually touching a bike for herself.

When Mary is given a bicycle for the first time she probably won’t be able to ride it – even though she knows all the physical facts about riding bicycles. This is because knowledge of how to ride a bike isn’t the kind of knowledge you can learn from facts in books. It’s ability knowledge. And ability knowledge is a kind of physical knowledge.

Applied to the original Mary case, some argue when Mary sees red for the first time all she does is gain new abilities. She gains the ability to imagine red, for example. She also gains the ability to distinguish red sensory experiences from green sensory experiences.

Question 22

acquaintance hypothesis response to the knowledge argument

Answer 22

Similar to the argument above, we can claim that although Mary learns something new, her new knowledge is still a kind of physical knowledge: knowledge by acquaintance.

Chances are you don’t know King Charles III personally – even if you know a load of facts about him. Even if you learned every physical fact about King Charles III you still couldn’t say you know him if you’d never met him.

But King Charles III’s acquaintances and friends do know him personally. But there’s nothing spooky or non-physical about their knowledge.

You can make a (sort of) similar argument for Mary’s experience of seeing the colour red.

She can know all the physical facts about red – what it is, when people see it, how they react to it, etc. – without being acquainted with redness itself.

Mary is not acquainted with redness because her own brain has never had this property itself. But when she sees red for the first time the property occurs in her brain and she becomes acquainted with redness. Mary gains new knowledge from being acquainted with redness in this way.

Question 23

problems for property/ epiphenomenal dualism

Answer 23

If epiphenomenalism is true, qualia have no causal effects
If qualia have no causal effects, then knowledge of mental states is impossible
But knowledge of mental states is possible (e.g. I can know “I am in pain”)
So, epiphenomenalism must be false

Question 24

phenomenology of mental life

Answer 24

In addition to causing knowledge of our mental states (see above), qualia also seem to cause other mental states.

For example, if someone is in constant chronic pain, this may cause them to feel sad. It seems plausible that the unpleasant feeling of being in pain (i.e. the qualia) caused the mental state of sadness – this explanation is perfectly reasonable.

But, if epiphenomenalism is correct, qualia have no causal powers. So this explanation can’t be correct – it wouldn’t be possible for pain qualia to cause sadness (or any other mental state). But this conclusion seems false: It seems obvious that qualia do cause other mental states, and so epiphenomenalism must be false.