Imre Lakatos (1922-1974)
The rationality of science
Zoltán Dienes, Philosophy of Psychology
Popper (1934) said scientists must commit in advance as to what
results would falsify a theory – then stick with that decision
Kuhn (1962) said science is best understood in terms of large-scale
“paradigms” relatively resistant to falsification but are kept or
discarded according to power struggles
Lakatos (e.g. 1970):
1) Falsifiability is very important
“Blind commitment to a theory is not an intellectual virtue it
is an intellectual crime”
BUT we need not stick with our original decisions
2) Large scale relatively unfalsifiable research programmes
are important in characterising science
BUT there is a rational basis to their rejection
Popper’s falsificationism (as construed by Lakatos)
Popper was a fallibilist: we might be wrong about any piece of
knowledge. Theories must be made to stick their neck out. But we
can only criticise one thing (e.g. a theory), if we take for true other
things. To be critical about anything, we must decide to accept other
things.
Methodological falsificationism
Popper was a fallibilist: we might be wrong about any piece of
knowledge. Theories must be made to stick their neck out. But we
can only criticise one thing (e.g. a theory), if we take for true other
things. To be critical about anything, we must decide to accept other
things.
Decision 1
Decide what can be legitimate independent and dependent variables
Scores on a certain extroversion scale
Reaction times
Decision 2
Decide which measurements you will accept.
Take a measurement. But do you trust that reading/score? Safety control:
repeat the measurement/experiment (matter of convention how many
times)
In taking these measurements fallible theories are involved; but for the
sake of testing another theory we take them as unproblematic
background knowledge.
How can we reject probabilistic theories?
Decision 3: Accept a certain level of significance e.g. p < .05
Decision 4:
Check assumptions of tests, data well behaved, background
knowledge safe.
Decide to accept all is in order so can be guided by the test
outcome.
Then results against a theory falsify it.
We must “reject the theory and not work on it again on pain of
being irrational.” (Lakatos’ description of Popper)
We set out to test the theory that extraverts are evening people
and introverts morning people.
We are happy with all four decisions and get results contrary to
expected:
No relation between extraversion and most productive time of
day
MUST we reject the theory?
We set out to test the theory that extraverts are evening people
and introverts morning people.
We are happy with all four decisions and get results contrary to
expected:
No relation between extraversion and most productive time of
day
MUST we reject the theory?
Some one proposes a possibly better measure of extraversion.
Might we test which measures is best
Find the new measure is better at measuring extraversion
then use the new improved measure in our experiment?
NB
Popper (1960) onwards softened his position:
One can work on a falsified theory if it has passed more
tests than its competitors
One theory can be closer to the truth than another
Also:
Popper (1970)
Any aspect of background knowledge provisionally
assumed as safe can be opened up for critical discussion at
a later stage
According to Lakatos (1970), the original 1934 Popperian account
differs from the history of science in several ways.
Lakatos:
Historically all theories have been ‘born falsified’ into an ‘ocean
of anomalies’.
Scientists can rationally work on a theory already ‘falsified’ and
also change their mind about the conditions that would falsify a
theory.
A scientific theory can become a hard core of a research
programme, treated (for some time) as immune to falsifications.
The methodology of scientific research programmes
A research programme has a hard core and a protective belt
Hard core: the central beliefs of the programme –
e.g.
In connectionism: psychological states consist of activation flowing
between units through adjustable weights
Dopamine theory of schizophrenia: Schizophrenia results from
imbalances in dopamine
We are ‘forbidden’ from falsifying the hard core
Protective belt:
Specific theories based on the hard core.
Must invent auxiliary hypotheses that form a protective belt
around the core, and direct falsifying conclusions to them – they
get adjusted, re-adjusted or replaced to defend the thus hardened
core.
For example, a specific connectionist network of children
learning to read
Postulating of specific dopamine receptors or pathways as
involved in specific symptoms of schizophrenia
If evidence goes against any of these theories, the specific
theories are falsified, not the hard core generally
The notion of a research programme emphasizes the continuity
and unity of theories over time:
“All swans are white” is falsifiable but not in itself science
(there is hard core generating a protective belt of falsifiable
theories)
A scientifically relevant unit of evaluation is the whole research
programme.
If an adjustment predicts some hitherto unexpected fact the change is
theoretically progressive;
if some of these predictions are corroborated, it is empirically
progressive.
Otherwise the adjustment is degenerating.
Thinking in terms of progressive or degenerating changes rather
than Popper’s falsification:
Less arbitrary.
Any of our decisions can be appealed. We don’t have to stick
with any of them.
The decisions can be overturned if that leads to a progressive
change.
(Contrary to Popper 1934) It is rational to work in a research
programme that is already “refuted” – anomalies can be pushed aside
with the hope they will turn into corroborations in the fullness of time.
(Contrary to Kuhn) research programmes have achieved monopoly
only rarely; the history of science is and should be the history of
competing research programmes. The sooner competition starts the
better.
Like Popper:
we must retain the determination to eliminate, under certain
objectively specifiable conditions, certain research programmes.
Like Popper:
we must retain the determination to eliminate, under certain
objectively specifiable conditions, certain research programmes.
A research programme is given up if it is degenerating while another
is progressive.
It is only when a progressive programme explains the failures of a
degenerating one that the degenerating one is treated as falsified.
Evolutionary
psychology
Parental investment
theory and mate
selectivity
Attractiveness
of symmetry
Timing of
sex with
lovers and
long term
partners
The mind evolved by
natural selection;
Cheater
detection
module
Most fundamental
human characteristics
evolved in the Hard
Pleistocene core
Human
sperm
competition
Protective belt
Positive heuristic: Think more carefully how Pleistocene conditions map onto
modern day life; could the apparent adaptation really be a consequence of another
adaptation; was the experiment ecologically valid
One approach to
learning
When learning complex
grammars, people learn
small chunks of words
People often
base
decisions on
memorized
exemplars
All learning is
conscious
Conditioning
results from
conscious
hypothesis
testing
Hard
core
Protective belt
Positive heuristic: Is something else simple people may have learned?
How could the test of conscious knowledge be made more sensitive?
Note on novelty:
Progressive means making novel predictions that are confirmed.
But what exactly counts as a novel prediction and why is novelty
important?
Early Lakatos: A novel prediction must be predicting a finding never
discovered before (“temporal novelty”).
Late Lakatos: A prediction is novel for a theory if it was not used in
constructing the theory (”use novelty”).
Contrast Bayesian theory