David ArmstrongThe Nature of Mind

Key elements of the text

Reference: Ross Phillips, La Trobe University, Sept. 2006Additions, editing: T. Hill, 2012

The main argument

P1: Mental states are the inner causes of behaviour.P2: The inner causes of behaviour are brain states.

C: Mental states are brain states.

This form of argument is logically valid, but is it sound?

Hypothetical syllogism:

P1: M=BP2: B=S M=S

The logic of the argument:

sound = true premisesvalid = correct logical structure

Be careful: This is NOT the main argument

Another example:

• Conclusion: The tooth fairy is just my mum.(This is a deflationary story, or reduction).

• Conclusion: There is no tooth fairy.(Elimination).

Not Armstrong’s argument:

•Mental states are brain states.

(A deflationary story or reduction).•There are no mental states.

(Elimination).

This is NOT Armstrong’s argument. He DOES NOT dismiss the existence of mental states; he claims that they are the same thing as brain states.

Armstrong’s thesis

• His thesis is that mental states are brain states.(a materialist who accepts that we have a mind)

• This is similar to saying that lightning is electrical discharge or that whales are mammals.

• Just because we can use different terms or conceptual language to explain something doesn’t mean they are not the same thing.

The Structure of the Essay

1. An argument for premise 2: that inner causes of behaviour are brain states.

2. An argument for premise 1: that mental states are inner causes of behaviour.

3. A reply to an objection to his thesis.

• The argument for premise 2 is based on the authority of science.

• The argument for premise 1 is based on a rejection of Behaviourism.

• The argument in the Reply asserts that consciousness can be compared with sense perception and can be explained in terms of a physical state of the central nervous system.

The argument for premise 2P1: In science there is a convergence of learned

opinion.P2: It is rational to believe what the learned

agree on.It is rational to believe what scientists agree

on.P3: Scientists agree that the inner causes of

behaviour are brain states.It is rational to believe that ICB = BS

The rejection of Behaviourism• Armstrong evaluates Behaviourism and declares

that their account of the mind is insufficient as it denies the existence of mind beyond observable physical behaviour.

• Armstrong’s criticism of behaviourism takes into account the usual criticisms and also references the ‘common experience’ that our thoughts are indeed separate from our behaviour.

• Armstrong’s conclusion accepts that thoughts are not the same as behaviour, they ‘lie behind’ behaviour, or ‘cause it’.

Behaviourism

How do we determine that there is a thinking person?Through observed behaviour.

Conditioning provides evidence for behaviourism:

Behaviourism

• Behaviourists deny that there is a mind that decides what action to perform in response to a stimulus (something that will elicit a response).

• They assert there is only stimulus and response and that by inserting a ‘mind’ that can decide on a course of action or a response is an unwarranted assumption at best, or a categorical mistake at worst. The result is the same: there is no such thing as a ‘mind’ as we would traditionally conceive it – or as Descartes would.

Behaviourism

But…•Why don’t people always act in the same way? If the stimulus is the same, why don’t people act in the same way?•Operant conditioning, learned behaviours through reward and punishment, can explain this to an extent, thanks to the work of B. F. Skinner and others.•The other reason argued by behaviourists is ‘dispositions’.

Dispositions and circumstances• Subject One

Receives a second phone bill after paying the first one already.

Gets angry. Refuses to pay.

• Subject Two

Receives a second phone bill after paying the first one already.

Appears relaxed and calm.

Both subjects are in circumstances which would usually cause anger. Why didn’t both react the same way?

The circumstances of the stimulus were not sufficient to elicit the expected response.

Answer: dispositions.

Dispositions in behaviourism

• GLASS

• Glass has a disposition to shatter in certain circumstances.

• If the glass doesn’t shatter, this can be explained by the circumstances.

• BEHAVIOUR

• People have a disposition (learned behaviour) to certain behaviours.

• If they don’t perform the behaviours, this can be explained by the circumstances.Note that in this case, it is external things

which explain the lack of expected behaviour, not the object itself.

Dispositions

Armstrong reframes mental events to differentiate them from behaviour, using the behaviourist notion of disposition.

Behaviourists analyse dispositions conditionally.

Armstrong analyses dispositions causally.

Armstrong’s dispositions

Armstrong’s argument:•The brittleness of glass can be explained by a state of the glass; its molecular construction.•“A disposition of an object is a state of the object.”•“But the disposition itself is distinct from its manifestations: it is the state of glass that gives rise to these manifestations in suitable circumstances.”

Armstrong in his own words:

• “This way of looking at dispositions is very different from that of Ryle or the Behaviourists. The great difference is this: If we treat dispositions as actual mental states, as I have suggested that scientists do, even is states the intrinsic nature of which may yet have to be discovered, then we can say that dispositions are actual causes or causal factors, which in suitable circumstances, actually bring about those happenings that are the manifestations of the disposition. A certain molecular constitution of the glass that constitutes its brittleness is actually responsible for the fact that, when the glass is struck, it breaks.”

And further…

• “The behaviourists were wrong to identify the mind with behaviour. They were not so far off the mark when they tried to deal with cases where mental happenings occur in the absence of behaviour by saying these are dispositions to behave… these dispositions [are] actual states of the person who has the disposition, states that have actual causal power to bring about behaviour in suitable circumstances.”

An illustration for comparison

• Behaviourism:

• Armstrong:

(“inner state apt for producing certain behaviour…”)

In standard form

P1: Mental states are dispositions to behave (in selected ways). Agrees with behaviourists.

P2: Dispositions are inner states which cause their defining effects. Disagrees with behaviourists.

Mental states are the inner causes of their defining effects.

P3: The defining effects of mental events are behaviour.

Mental states are the inner causes of behaviour.

In summary..

Armstrong agrees with the main tenants of behaviourism, that the defining effects of mental events are behaviour, but disagrees with their analysis of dispositions. He also aligns with Descartes in thinking that there is an ‘inner arena’ and that thought ‘lies behind’ behaviour. He differs with Descartes in arguing that the contents of this inner arena can be explained physically.

Part 3: Response to an Objection: The Problem of Consciousness

Armstrong uses his dispositional analysis to account for consciousness. Under his conception, consciousness is compared with sense perception, and is explained in terms of a physical state of the central nervous system.So, just as our sense perception enables us to distinguish between different sounds and colours and as such is a physical state of the central nervous system, so our consciousness allows us to differentiate between our own mental states.

Consciousness

• Armstrong explains it as a self-scanning mechanism of the CNS, as an ‘inner eye’ that can monitor the activities of our other brain states.

• Consciousness then is like perception, except that it is perception of one’s own mental state. You can ‘scan’ your inner states in the same way you can ‘scan’ a physical environment and differentiate between things such as colour.

In summary…

To handle the first person experience of mind:Consciousness is the perception of one’s own mental state.

To handle the third person observation of mind:Dispositions are states apt for the production of a range of behaviours.

In summary: Armstrong’s thesis1. Human beings are a physico-chemical

organism. All of our mental events are reducible to events in the brain.

2. Mental events are:a) physical states of the Central Nervous Systemb) ‘states of the brain apt for producing certain

types of behaviour’.3. Consciousness is a self scanning mechanism of

the CNS.