How well has Hume’s
psychology of causation
withstood the test of time?
The plan
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Introduction
Hume’s psychology of causation
Causal perception
Causal inference and associative learning
Causal inference and causal perception
Innateness
1 Introduction
Hume way more interested in the
psychology of causation than the
metaphysics and semantics.
Doing the ‘science of man’.
(Actually main target is epistemological, but
he thinks – wrongly – that the psychology
has a bearing on this.)
2 Hume’s psychology of causation
Starter question:
How do we get to have beliefs?
(where ‘belief’ = expectation)
Aim: to find a psychological mechanism which
delivers belief as output, but does not have belief
as input.
Input must be impressions/ideas/knowledge, since
we already know how they arise.
Answer: ‘Custom or habit’ or ‘A-mechanism’
(‘A’ for ‘associative’)
2 Hume’s psychology of causation
What’s wrong with this account (UP)?
(P1)
c occurs
(P2)
C’s have been constantly conjoined with E’s in my past
experience
(P3)
Instances which I haven’t experienced resemble those
I have experienced (Uniformity Principle)
(C)
e will occur.
Answer: (P3) is itself a belief, so can’t be input to a
mechanism that explains the origin of belief in general.
2 Hume’s psychology of causation
Hume’s account (the A-mechanism)
(P1)
c occurs
(C)
e will occur
Input:
Output:
Mechanism:
present impression (P1)
belief
habit or custom
Mechanism activated when past C’s have been conjoined in
my experience with past E’s (memory).
This explanation of belief is not circular: it does not have
belief as input. Job done!
2 Hume’s psychology of causation
Next up: causal perception & inference (A-mechanism again)
Quote …
I claim:
► The impression of NC gives us genuine causal
experience (or ‘perception’ in psych terms).
In ‘single instances of the operation of bodies’, all events
‘seem entirely loose and separate’. Not when the Amechanism is up and running!
►
Causal judgement involves the idea of NC.
So the A-mechanism delivers (a) expectations, (b) causal
perception, (c) causal judgements.
The A-mechanism
JUDEMENT:
c caused e
PERCEPTION:
c causing e
idea of NC
expectation (e)
impression of NC
HABIT
Past experience + present impression of c
2 Hume’s psychology of causation
That was all causation ‘considered as a natural relation’.
Finally: Conscious causal inference (C-mechanism: causation
as a ‘philosophical relation’).
Not immediate/instinctive; involves conscious reasoning.
E.g. inference about what C causes using evidence not involving C.
Coffee (C) + cake (B) = wide awake (in past exp)
Cake alone = zzzzz (in past exp)
 Coffee causes being wide awake
(Every event has a cause; isn’t cake; so must be coffee.)
Only beings with A-mechanism can have C-mechanism (else
no beliefs possible; also no idea of NC).
But can have A-mechanism without C-mechanism (dogs)
2 Hume’s psychology of causation
Consequences:
(a)
There IS such a thing as causal perception
(b)
2 mechanisms responsible for causal inference
(A and C: A instinctive/immediate, C involves extra
cognitive ability)
(c)
Causal perception (sometimes) separable from causal
inference (thanks to C-mechanism)
(d)
Neither perception nor inference innate
(Past experience of regularity required)
3 Perception of causation
There is such a thing, for Hume.
Surprise!
Philosophers: ‘all events seem entirely loose and separate’
(forgetting the surrounding text)
Psychologists: Michotte’s take (existence of causal
impression refutes Hume) is standard (cf. Danks).
(Ambiguity of ‘perception’ doesn’t help here. No perception
of causation in philosophers’ sense.)
Hume seems to have got this bit right!
3 Perception of causation
Question is not:
Do we perceive causation? (in psych sense), but
What’s the mechanism?
And in particular:
Can we have CP in the absence of past experience of
regularity?
Jury’s out. Hard to get evidence!
Saxe and Carey (2006):
‘by the time experimentalists can find robust evidence of
causal perception, infants have already had six months of
experience observing causal interactions’
 Hume still in the running on this.
4 Causal inference & associative learning
A-mechanism pretty crudely Pavlovian, but associative
learning still generally thought to play a role in causal
inference.
But seems not to be the whole story.
Blicket detector/backward blocking:
(a)
A + B = music plays
A alone = music plays
vs.
(b)
A + B = music plays
A alone = music doesn’t play.
Is B a blicket? Different answers to (a) and (b).
Hume doesn’t have a specific story here, but he does have
an additional mechanism for causal inference (association
not the only route to causal inference).
5 Causal inference & causal perception
What’s the connection?
Same mechanism or distinct?
One a subset of the other?
One necessary for the other?
Under-explored. One way to answer it: try to find situations
that prompt only causal perception or only causal
inference.
Schlottmann & Shanks (1992) get this result.
Compatible with Hume (if cut some slack):
A-mechanism: delivers causal perception (& inference).
Irresistable
C-mechanism: can override A-mech inference, but not
perception (too late!).
6 Innateness
Big challenge to Hume (though jury out):
Perhaps (some) causal perception & inference is innate.
Maybe don’t need past experience to get:
► (some) CP (launching event)
► (some) causal inference (born with assumptions about
causal structure).
But …
Hume’s scruples re innateness are (mistakenly) based on
epistemological scruples re rationalism.
He could accept some innateness without weakening his
arguments against causal rationalism.
Maybe he should have done (but hardly his fault) …
6 Innateness
Hume’s thesis:
A priori knowledge of the causal structure of the world is
impossible.
Standard early modern view:
Innate = a priori.
If belief that p is innate, then p is known a priori.
So Hume thinks he needs to hold that causal inference (and
so perception) is acquired, not innate.
But he doesn’t! Confuses genesis of belief with justification:
► We can learn p through experience yet p have a priori
justification (1 + 2 = 3).
► We can have innate belief’ that p, yet p be justifiable only
a posteriori.
6 Innateness
“As this operation of the mind, by which we infer like effects from like
causes, and vice versa, is so essential to the subsistence of all human
creatures, it is not probable, that it could be trusted to the fallacious
deductions of our reason, which is slow in its operations; appears not,
in any degree, during the first years of infancy; and at best is, in every
age and period of human life, extremely liable to error and mistake. It
is more conformable to the ordinary wisdom of nature to secure so
necessary an act of the mind, by some instinct or mechanical
tendency, which may be infallible in its operations, may discover itself
at the first appearance of life and thought, and may be independent of
all the laboured deductions of the understanding.”
If the ability to infer like effects from like causes were innate (preprogrammed expectations; no experience necessary), that would be
even more conformable to the wisdom of nature!
(Though if the ‘idea’ of causation were innate, e.g. born with
assumptions about causal structure (and not just pre-programmed
expectations), that would rather undermine his entire account ...)
Conclusion
Given that Hume:
► was writing more than 250 years ago, and
► deployed a really dubious scientific method (viz,
introspection),
he did a pretty good job with the psychology of causation!
►
►
►
Right about causal perception
At least partly right about the role of associative learning
At least partly right about the relationship between causal
inference & perception.
(Though might be wrong about innateness …)
Not bad!