Metaphysics of Mind

Mental States & Phenomenal Properties

All or at least some mental states have phenomenal properties, meaning there is a subjective, first-person aspect of experience.

Qualia (spec)

The intrinsic and non-intentional phenomenal properties of experience that are introspectively accessible.

Qualia

The subjective, first-person qualities of conscious experience. What it feels like to have a particular mental state.

Intentionality

The feature of some mental states (like beliefs and desires) by which they are about, of, or directed at something (objects, states of affairs, or propositions).

Phenomenal properties

Properties which concern what an experience feels like.I

Intentional properties

Properties which concern what a mental state is about.

Interactionism

The physical and mental cause each other. They interact.

Epiphenomenalism

The physical causes the mental. The mental has no causal role.

Property dualism

The view that there is one kind of substance (physical), but it has both physical and non-physical (mental) properties that are not reducible.

Substance dualism

The view that there are two distinct substances, physical (body) and non-physical (mind), which exist independently.

Problem of other minds

Dualism claims mental states are private and not directly observable, so we only see behaviour. Therefore we cannot be certain others have minds, leading to solipsism.

Argument from analogy

We know our own mental states cause our behaviour, and others behave similarly so we infer by analogy that they have similar mental states.

Best hypothesis response

Dualists can claim the best explanation of behaviour is that others have minds like ours. Alternative explanations fail, but this is not logically provable.

Category mistake

Substance dualism claims the mind is a separate substance alongside the body. Ryle argues this is a category mistake, as the mind is just behaviour and dispositions.

Conceptual interaction problem

Interactionist substance dualism claims the non-physical mind causally interacts with the body. But a non-extended mind cannot make contact, so interaction seems impossible.

Empirical interaction problem

Interactionist dualism claims mental events can cause physical events. But a non-physical mind cannot transfer energy, so this conflicts with conservation of energy.

Introspective self-knowledge

Epiphenomenalism claims mental states have no causal power, yet we voice them. This suggests mental states cause behaviour, so self-knowledge of mental states doesn’t make sense.

Phenomenology of mental life

Epiphenomenalism claims mental states do not cause anything. But our experience suggests mental states cause actions and other mental states.

Natural selection and evolution

Epiphenomenalism claims mental states have no causal role. But evolution only selects traits that affect behaviour, so consciousness becomes hard to explain.

Functionalism

The view that mental states are defined as the combination of inputs, mental states and outputs happening in sequence.

Multiple realisability

The same mental state can be realised by different physical structures, as long as they perform the same functional role.

Qualia

The subjective, first-person qualities of conscious experience. What it feels like to have a particular mental state.

Inverted qualia

The possibility that two individuals could have identical functional states but different subjective experiences.

Inverted qualia example

Two people are looking at a tree, and they both believe and see and say it is green. One person sees green and the other person is colour blind and sees what the other would actually call red. However, because both have always labelled that experience “green”, their behaviour and responses are identical even though their subjective experiences differ.

Inverted qualia challenge to functionalism

If two people can have the same functional organisation but different experiences, then mental states may involve more than functional roles.

China brain thought experiment

Every neuron in a brain is replaced by a person in China who follows instructions so that the whole system reproduces the same functional organisation as a human brain.

Functional duplicate with no mentality

If functionalism is correct, a system that reproduces the same functional organisation as a brain should have the same mental states and consciousness.

China brain challenge to functionalism

Many people think that the coordinated population of people in China as a whole would not literally feel pain or have experiences, even if it replicated the functional organisation of a brain. This suggests functional organisation alone may not be sufficient for consciousness.

Mary argument applied to functionalism

Mary knows all possible functional facts about colour perception, including every input, internal process, and behavioural output involved in seeing colour.

Mary gaining new knowledge

When Mary sees red for the first time, she appears to learn what the experience of red is like, even though she already knew all the functional information.

Mary challenge to functionalism

If Mary can know all functional facts but still learn something new about the experience, this suggests that functional descriptions do not fully capture qualia, so mental states may involve more than functional roles.

Eliminative materialism

The view that some or all folk-psychological mental states do not exist and our common-sense understanding of the mind is radically mistaken.

Core claim of eliminative materialism

Mental states like beliefs and desires are not real; neuroscience will replace mental language.

Folk psychology

The human capacity to explain and predict the behaviour of other people using non-scientific or non-technical terms.

Certainty about mental states

We are directly aware of our own experiences and the existence of mental states seems more certain than any scientific theory. Denying mental states seems less plausible than denying neuroscience. 

Unreliability of introspection for mental states

Introspection is unreliable and science often overturns common sense. Future neuroscience will explain why we think we have mental states, we're just not there yet. 

Explanation by reasons (beliefs, desires)

Folk-psychology explains mental states in terms of reasons. If reasons really explain behaviour, they probably refer to something real. Folk psychology is the best hypothesis.

Eliminative materialism response to the best hypothesis

Reasons only describe behaviour patterns. Neuroscience will eventually explain the real causes in terms of brain processes.

Self-refuting nature of eliminative materialism

The articulation of eliminative materialism as a theory is self-refuting; stating it requires a belief in it, which eliminative materialists believe is not real (believing things).

Limitations of current understanding of eliminative materialism

We are not yet neuroscientifically advanced enough to have the language to correctly state eliminative materialism.

Mind–Brain Type Identity Theory

The view that each type of mental state is identical to a type of brain state. Mental states are ontologically reducible to brain states.

Ontological Reduction

The terms refer to the same thing but are not interchangeable in a sentence. The terms cannot be swapped and keep identical meaning.  

Dualist criticism of identity

Correlation between mental and brain states does not prove they are identical. It only shows correlation.

Dualist view of MBTIT

Dualists object that even if every mental state correlates with a brain state, this does not show identity, because the qualia is not captured by physical brain descriptions. 

Multiple realisability

The same mental state can be realised by different physical brain states, meaning there isn’t a 1:1 correlation.

Human brain activity as a response

In humans, every mental state still requires some corresponding brain activity.

Supervenience

X supervenes on Y if and only if a change in Y is necessary for a corresponding change in X to be possible. 

The philosophical zombies argument

P1: It is possible to conceive of a zombie.

P2: A zombie is physically identical to a human, but without the mental property of consciousness.

P3: Conceivability implies the idea that it is metaphysically possible.

P4: Consciousness is a mental property.

P5: If a physical brain without consciousness is conceivable, then consciousness must be separate from the physical.

C: Therefore, property dualism is true.

A zombie world is not conceivable

If consciousness relies on the physical processes in our brain, then a 'zombie' physically identical to a human must have consciousness. We can only conceive of it because we don’t understand it.

What is conceivable may not be metaphysically possible

Just because we can imagine something doesn’t mean it could really exist. One might conceive of a right-angled triangle without a hypotenuse but that’s impossible once we know Pythagoras' theorem. It was conceived before it was understood, therefore, conceivability doesn’t guarantee metaphysical possibility.  

What is metaphysically possible tells us nothing about the actual world

Even if a zombie world is metaphysically possible, that doesn’t prove that it is actually true of our world. It’s possible unicorns could exist, but that doesn’t mean they do, and it doesn't mean they're relevant to the real world.

The Mary argument

P1: Someone who knows everything physical about colour without seeing it would have 100% physical knowledge.

P2: Upon seeing colour for the first time, they would gain knowledge.

P3: This cannot be physical knowledge since they already have 100% of this.

C: Therefore, there is non-physical knowledge, and physicalism is false.

Mary gains ability knowledge (objection)

When Mary leaves her black-and-white room and sees colour, she gains no new propositional knowledge. Instead, she gains new ability knowledge: the ability to recognise or imagine red, the ability to remember red, the ability to compare shades of red

Mary gains acquaintance knowledge (objection)

When Mary sees colour for the first time, she becomes acquainted with a new property: the qualia of seeing red.

Mary finds a new way to know her knowledge

Mary just comes to know her physical knowledge under a new mode of presentation. She already knew all the physical facts about colour vision, but lacked the qualia to represent them from the first-person perspective.

Property Dualism

At least some mental properties are not reducible to, nor dependent on, physical properties.

Example of supervenience

A painting’s beauty cannot change without a corresponding change in the physical arrangement of paint or light.

Property dualism against supervenience (mental on physical)

Mental states could change without any change in the brain. Therefore, two physically identical brains could have different mental states

Philosophical zombies

Beings physically identical to humans but with no consciousness.

Key claim of the zombie argument

If zombies are conceivable, consciousness must non-physical.

Key claim of the Mary argument

Physicalism is false because Mary learns something non-physical when she sees colour.

Substance Dualism

The view that there are two fundamentally different types of substance: physical substances or bodies and mental substances, or minds.

Substance

Something that does not depend on another thing in order to exist, which possesses properties and persists through changes. 

Property

An attribute or characteristic of a substance. Depends on the substance in order to exist.  

Indivisibility Argument

• P1. It is a law of logic that if x and y have exactly the same properties then x=y  

• P2. If there is a property P that x has but that y does not have then x is not numerically identical to y.  

• P3. My body is always divisible.  

• P4. My mind is always indivisible.  

• C1. Therefore, my body cannot be the same substance as my mind.  

The mental is divisible in some sense

Modern neuroscience shows brain damage can impair parts of the mind, effectively dividing it. There is also split-brain surgery and multiple personality disorder which show a division of consciousness. 

Not everything thought of as physical is divisible

Things like elementary particles like atoms, or electromagnetic fields aren’t legitimately divisible, yet they’re physical. 

The conceivability argument

• P1. If I can clearly and distinctly recognise the nature of two things to be different then they are different   

• P2. I can conceive (clearly and distinctly recognise) that my mind, a thinking non-extended thing, can exist without my physical non-thinking extended body existing.   

• C1. Therefore it is metaphysically possible for my mind to exist without a body.   

• P3. If it is metaphysically possible that X exists without Y, then Xand Y are not identical.   

• C2. Therefore, my mind is not identical with my extended body.   

Mind without body is not conceivable

The separation of mind and body is only apparently conceivable, not genuinely. Clear and distinct conceivability requires full understanding, which we lack regarding the nature of the mind.

What is conceivable may not be metaphysically possible

Just because we can imagine something doesn’t mean it could really exist. One might conceive of a right-angled triangle without a hypotenuse but that’s impossible once we know Pythagoras' theorem. It was conceived before it was understood, therefore, conceivability doesn’t guarantee metaphysical possibility.

What is metaphysically possible tells us nothing about the actual world

Even if minds without bodies are metaphysically possible, that doesn’t prove they actually exist. It’s possible unicorns could exist, but that doesn’t mean they do.

Physicalism

Everything is physical or supervenes on the physical.

Hard behaviourism

The view that all propositions about mental states can be reduced without loss of meaning to propositions that exclusively use the language of physics to talk about bodily states/movements.  

Soft behaviourism

The view that statements about mental states can be reduced to statements about behavioural dispositions. 

Ryle’s category mistake

Dualists treat the mind as if it were a separate entity like the body, when in fact mental concepts belong to a different category: they describe behavioural dispositions, abilities and tendencies, not inner objects.

Analytic Reduction

A claim that words of one sort mean the same as words of another sort. This means that we could change the language in a sentence from one to the other and the sentence would still keep its meaning. 

Ontological Reduction

The terms refer to the same thing but are not interchangeable in a sentence. The terms cannot be swapped and keep identical meaning.

Soft behaviourism’s definition of mental states

Tendencies to behave a certain way in certain conditions

The physicalist claim about mental states

Thoughts, sensations and emotions depend entirely on brain and nervous-system processes.

What physicalism denies

The existence of any non-physical “mental substance”.

How hard behaviourism treats mental vocabulary

Terms like “belief” and “pain” are shorthand for observable behaviour.

The conceivability argument against behaviourism

We can conceive of having mental states without producing any behaviour. If the mental can exist without the physical, then mental states cannot be identical to behavioural states or dispositions.

The introspection argument against behaviourism

When we introspect, we have direct access to our mental states without needing to observe our behaviour. This suggests that to understand our own mental state, we do not need to know the behaviour.

The interaction argument against behaviourism

In everyday experience, we take mental states to cause behaviour as pain causes wincing; a desire causes action. If behaviourism says mental states are behaviour or dispositions, it cannot explain this causal role that mental states have.

The circularity argument against behaviourism

To specify the right behaviour we usually end up referring back to the mental state we are trying to define, for example: “Fear is the disposition to behave as someone who is afraid would behave.”

The multiple realisability argument against behaviourism

Because a single mental state corresponds to many different behaviours, it can’t be neatly reduced to one behavioural description undermining (especially hard) behaviourism’s reduction claim. 

The asymmetry argument against behaviourism

We know our own mental states directly through introspection and first-person awareness because we can feel it. But we only know others’ mental states indirectly, by observing their behaviour. If behaviourism were true, there would be no difference between how we know our own mental states and how we know others’.

Super Spartans against behaviourism

Putnam’s Super-Spartans feel pain without producing any pain behaviour at all; no crying, wincing, withdrawal, or reports of suffering. They have the mental state but not the behaviour. This shows that mental states can exist without behaviour, meaning they cannot be reduced to behaviour.

Perfect actors against behaviourism

A perfect actor can imitate pain behaviour flawlessly while not actually feeling pain. They exhibit the behavioural pattern without the corresponding mental state. This shows that behaviour can exist without the mental state.