David Armstrong
The Nature of Mind
Key elements of the text
Reference: Ross Phillips, La Trobe University, Sept. 2006
Additions, 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.
Hypothetical syllogism:
The logic of the argument:
P1: M=B
P2: B=S
 M=S
This form of argument is logically valid, but is it sound?
valid = correct logical structure
sound = true premises
Be careful: This is NOT the main argument
Another example:
Not Armstrong’s argument:
• Conclusion: The tooth
fairy is just my mum.
(This is a deflationary
story, or reduction).
• Conclusion: There is no
tooth fairy.
(Elimination).
• 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 2
P1: 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
• Subject Two
Receives a second phone
bill after paying the first
one already.
Receives a second phone
bill after paying the first
one already.
The circumstances
of the stimulus
were not sufficient
to elicit the
expected
response.
Gets angry. Refuses to pay. Appears relaxed and calm.
Both subjects are in circumstances which would usually cause
anger. Why didn’t both react the same way?
Answer: dispositions.
Dispositions in behaviourism
• GLASS
• BEHAVIOUR
• Glass has a disposition
to shatter in certain
circumstances.
• If the glass doesn’t
shatter, this can be
explained by the
circumstances.
• 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:
Dispositions
(brittleness)
Glass
Conditions
(dropped
from height)
Resultant
behaviour
(shatters)
• Armstrong:
Possible
behaviour
Conditions
Person
Disposition = Mind
defined as state
(“inner state apt for producing
certain behaviour…”)
(second phone
bill arrives)
Possible
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 thesis
1. 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 System
b) ‘states of the brain apt for producing certain
types of behaviour’.
3. Consciousness is a self scanning mechanism
of the CNS.