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Imre Lakatos (1922-1974) The rationality of science Zoltán Dienes, Philosophy of Psychology.

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Presentation on theme: "Imre Lakatos (1922-1974) The rationality of science Zoltán Dienes, Philosophy of Psychology."— Presentation transcript:

1 Imre Lakatos ( ) The rationality of science Zoltán Dienes, Philosophy of Psychology

2 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

3 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

4 Poppers 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.

5 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

6 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.

7 How can we reject probabilistic theories? Decision 3: Accept a certain level of significance e.g. p <.05

8 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)

9 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?

10 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?

11 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

12 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.

13 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

14 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

15 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)

16 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.

17 Thinking in terms of progressive or degenerating changes rather than Poppers falsification: Less arbitrary. Any of our decisions can be appealed. We dont have to stick with any of them. The decisions can be overturned if that leads to a progressive change.

18 (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.

19 Like Popper: we must retain the determination to eliminate, under certain objectively specifiable conditions, certain research programmes.

20 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.

21 The mind evolved by natural selection; Most fundamental human characteristics evolved in the Pleistocene Hard core Evolutionary psychology Protective belt Parental investment theory and mate selectivity Cheater detection module Human sperm competition Attractiveness of symmetry Timing of sex with lovers and long term partners Positive heuristic 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

22 All learning is conscious Hard core One approach to learning Protective belt When learning complex grammars, people learn small chunks of words Conditioning results from conscious hypothesis testing People often base decisions on memorized exemplars Positive heuristic Positive heuristic: Is something else simple people may have learned? How could the test of conscious knowledge be made more sensitive?

23 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


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