Issues facing dualism

The problem of other minds

We each experience our own thoughts and feelings. Even though you don't experience other peoples inner thoughts, you assume they have them (from their behaviour). But if substance dualism is true, what grounds do you have to make this assumption? 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. It seems substance dualism leads to scepticism about the existence of other people’s minds.

Response to the problem of other minds: John Stuart Mill's argument from analogy

Mill: There is a connection between mental states and physical behaviour. when i feel pain, my behaviour shows this - and others also do similar things. similar behaviours are caused by similar causes. therefore, it is rational to infer that others have minds like my own

Response to the problem of other minds: The existence of other minds is the best hypothesis

Best explanation of human behaviour is that people have minds. Either zombies, or minds. Best explanation is minds. (russell)

Dualism makes a category mistake: Gilbert Ryle

Ryle said Descartes idea of mind and body as separate was based on a category mistake. Ryle says "mind" doesn't name another kind of thing, Descartes was misusing language. He gives the example of someone visitng oxford university and says "where is the university?" when they see separate buildings. He was mistakenly allocating the university to the same category as that to which other institutions belong. He proposes behaviourism

What is a category mistake

Assigning the properties belonging to one category of things to something that is not a member of that category.

What is interactionalist dualism

Substance and Property dualism

Issues facing interactionalist dualism are:

the conceptual interaction problem, the empirical interaction problem

The conceptual interaction problem (Elisabeth, Princess of Bohemia)

P1. Physical things only move when something exerts force on them

P2. Only something that is extended can exert such force

P3. the mind is not extended

C1. therefore, the mind cannot move the body.

(but it does)

The empirical interaction problem

- The law of conservation of energy says that: In a closed system, energy cannot be added or removed - it can only be transferred

- Our universe is such a closed system

- If substance dualism is true, it would mean energy is constantly being added into the closed system of our universe every time the mental interacts with the physical

- So, if substance dualism is true, the law of conservation of energy is false

- But there is a lot of evidence to suggest that the law of conservation of energy is true

- So, substance dualism must be wrong

What is epiphenomenalist dualism

A form of property dualism which holds that mental states are produced by physical processes in the brain but have no causal influence on the physical world.

Analogy of epiphenomenalist dualism

The smoke doesn’t push the train along – it’s just a by-product of the engine. Similarly, qualia doesn’t cause anything – it’s just a by-product of brain activity.

difference between interactionist and epiphenomenalist dualism

Interactionist dualism: the mind can interact with the physical world and the physical world can interact with the mind. (the mental and physical can interact in both directions.)

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

Issue for epiphenomenalist dualism: challenge posed by introspective self-knowledge

Epiphenomenalism usually explains away the apparent causal effects of qualia by saying that it’s the brain that causes both qualia and behaviour.

- 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)

Epiphenomenalist Dualism Issue: the challenge posed by the phenomenology of our mental life

Qualia 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.

Epiphenomenalist Dualism Issue: challenge posed by natural selection/evolution

Evolution says that genetic mutations occur randomly. Over millions of years, the environment selects for genes that give some benefit – either in terms of survival or reproduction. But, if epiphenomenalism is true, there would be no evolutionary benefit to having qualia because epiphenomenal qualia doesn’t have any causal effect. This is because if consciousness plays no causal role, then it would be hard to explain why conscious experiences (like pain etc) will have evolved