Lecture 10: the revenge of the rationalists Flashcards
logical positivism fails because… (4 redenen)
– theoretical concepts are richer than summaries to observations & observations are not neutral: theory-ladenness
– Underdetermination of theory by observation
– the induction problem blocks verification of scientific statements
– Science is full of unobservable entities (which are supposed to be unverifiable)
- Popper worked in a daycare center with
Alfred Adler - Popper presented Adler with a case that
he felt didn’t fit into Adler’s theory. - Adler explained the case by modifying his
theory, showing great certainty - “Slightly shocked, I asked him how he
could be so sure. ‘Because of my
thousandfold experience’, he replied;
whereupon I could not help saying: ‘And
with this new case, I suppose, your
experience has become thousand-and-
one-fold.’” (Popper, 1978)
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“I found that those of my friends who were
admirers of Marx, Freud, and Adler, were
impressed by a number of points common to
these theories, and especially by their
apparent explanatory power…Once your eyes
were thus opened you saw confirming
instances everywhere: the world was full
of verifications of the theory. ” (Popper, 1978)
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wat vond popper dus over adler, freud en marx
- These theories can explain all facts
- This might sound as something
wonderful… - Popper, however, realizes: This is not a
strength, but a weakness!
wat gebeurde er net in de tijd dat popper actief was
- In the same period Einstein posits the theory of relativity
- This theory predicts that light deflects along a planet
- The solar eclipse of 1919 enables Arthur Eddington to test the prediction
- If the prediction didn’t come true, this would proof Einstein’s theory wrong
wat deed popper met dit ding van einstein
- So Einstein’s theory excludes certain events
- This is a strong theory exactly because it can not explain everything
- Karl Popper recognizes that this marks the essence of science
- After all, if you’re wrong, you can find out!
- With a theory that can explain everything this is impossible
- Such a theory is uninformative
induction en deduction verschil
induction: observation -> theory
deduction: theory -> observation
wat zei popper over induction
induction is onmogelijk, maar ook niet noodzakelijk: instead we can do deduction (use theories to derive predictions about observations)
- Theories are bold conjectures whose predictions can be tested against observations
- Popper: theory-free observation is impossible, but is also not needed
- Induction is impossible: you cannot induce theories from observations
- But that is ok, because instead we can do deduction: theories can be used to derive predictions about observations!
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hoe vond popper dat je van theorie naar observatie moest gaan
theories are not constructed from observations (wat de logical positivists zeiden), but they emerge from a creative act. and then predictions are derived from this, which are tested on the basis of observation.
dus wat was het grootste verschil tussen logical positivists en popper
logical positivists: empiricists, induction, observations -> theories
popper: rationalist, deduction, theory -> predictions (which are tested via observation)
waarom denkt popper dat hij het induction problem heeft opgelost
because it doesnt really matter how the theory arises, the only scientific act is refutation. this can be done by deducing predictions from the theory that can then be tested. and deduction is logically valid!
hypothetico-deductive model=
- start with theory
- deduce predictions from theory
- test these predictions
- if these predictions dont come true: falsify
- if they do come true: corroboration
corroborated theory =
(not the same as verification!!!)
a corroborated theory is one that is strong because it survived a risky test, but it is not accepted.
even kijken naar blaadjes
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empirical cycle
observation - theory construction - prediction - test - evaluate - observation…
door adriaan de groot
wat vond popper over theory development
helemaal vrij, moet gewoon creatief gebeuren.
popper vouched for hypothesis testing, werkte dus niet zo goed bij psychologie en filosofie (nu veel kritiek). popper is very normative (this is how you should do science), kuhn en lakatos meer descriptive (this is how science happens).
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popper tijdens…
ww2
waardoor werd popper eigenlijk aangezet
door een foutje in adler zijn theory
wat deed adler
explained all behaviour via inferiority complexes
wat is een verschil tussen theorieen maken en testen
– context of discovery (there is no logic for theory development)
– context of justification (strict rules for the logic of testing: modus tollens)
dus theorie bedenken is heel vrij, theorie testen is heel strict.
waarom is popper een rationalist
theories spring from the imagination, en daarna logisch over nadenken (part of the content of our theories comes from ratio, not from observation)
wat is een verschil tussen popper en bijvoorbeeld plato
- popper considers the ratio fallible
- his version of rationalism is called critical rationalism (nog steeds populair)
demarcation=
demarcation criterion distinguishes science from pseudoscience
wat was popper zijn demarcation criterion
falsification
falsification criterion=
statements or theories are scientific when they are in conflict with possible observations
a theory is scientific only…. (popper)
if the theory is falsifiable
welke problemen lost dit falsification criterion op
- induction (soort van)
- infinite sets
- unobservable entities
Falsificationism is a normative theory that prescribes how science should be done
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wat zijn degrees of falsifiability waar in kan worden gedifferentieerd
- precise
- general
precise =
specific predictions
general =
- conditions
- does it apply to a few, or a lot of people?
more precise and more general theories exclude more, therefore they are more falsifiable -> greater informative content.
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dus waar ben je naar op zoek bij deze situaties
de situatie die het meeste uitsluit, die het snelste kan worden gefalsificeerd. die is het “beste”
A) All women wear a red t-shirt
B) All women with blue jeans and brown hair,
wear a red t-shirt
A is meer falsificeerbaar
A) People who are primed with Einstein, score
higher on an IQ test.
B) People who are primed with Einstein and are not from Amsterdam and had a good night of sleep, score higher on an IQ test.
welke is beter en wat gebeurt er bij B?
A is beter, B is more conditional and therefore less general
dus meer conditional (meer dingen waar het van afhangt) =
less general (en dus minder goed)
A) All women wear a red t-shirt
B) All women wear a red t-shirt and blue jeans and have brown hair
welke is meer informative
B
A) People who are primed with Einstein, score
higher on an IQ test.
B) People who are primed with Einstein, score 6 points higher on an IQ test.
B
A) All women wear a red t-shirt
B) All women with blue jeans and brown hair,
wear a red t-shirt
A) All women wear a red t-shirt
B) All women wear a red t-shirt and blue jeans and have brown hair
welke B is meer precise, welke is meer general?
eerste B is less general
tweede B is meer precize (specific prediction)
wat zijn problemen met falsification
- popper cannot make a clear distinction between better supported and less supported theories
- at best, theories are ‘not yet refuted’
- hard falsification is very difficult
duhem-quine thesis
if a prediction does not become true, it could be the theory or the measurement/test.
-> a theory is never tested in isolation, always with additional background assumptions
wat is een implicatie van de duhem-quine thesis
hard falsification is impossible (you never know for sure whether your theory should be falsified, or that one or more background assumptions was wrong).
dus de duhem quine problem is to… as … was to …
duhem quine problem - popper
induction problem - logical positivists
wat is nog meer een lastig puntje aan poppers theorie
- as a scientist you have to falsify your OWN theory
- basically having bankers reducing their own bonuses, mensen zijn trots op wat ze hebben gemaakt en geloven hier in. gaan dit dus nooit 100% willen falsificeren.
‘We should ring the bells of victory every
time a theory is refuted’ – Popper, 1946
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popper says he has a normative theory, but does not describe examples of what we have considered as scientific successes.
dus falsificationism is not historically accurate
dus 2 problemen popper
- duhem quine thesis
- geen differentiation between better and less supported theories
- falsificationism is not historically accurate
- Historian Thomas Kuhn claims that science is not as the logical positivists (or Popper) claim
- Against positivism: Theories often break with their predecessors
- Paradigm shifts
- For example: from Newton to Einstein
- In this transition, the meaning of a term like “time” changes
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Kuhns’ stages of science
– Pre-science
– Normal science I
– Anomalies and crisis
– Revolution
– Normal science II
- It is not entirely clear whether Kuhn believes in progress over paradigms. At least it is not
guaranteed by the scientific method. - His book ‘the structure of scientific revolutions’ is the single most widely cited book in the social sciences
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what movement emerges, that is associated with kuhn
relativism
waarom kan je niet spreken van progress tijdens deze paradigm shifts
- You cannot speak of scientific progress
because if terms change meaning in theories,
those theories are not even about the same
thing - In another paradigm you see another world
dus je spreekt over compleet andere dingen.
Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same
direction
kuhns paradigm =
all-encompassing schemes like Newtonian mechanics
wat is lastig bij psychologie
- Psychology actually only has local paradigms
- And: paradigms in psychology seem to be
mostly methodological rather than substantive
Feyerabend writes the book Against Method…
- Denies the existence of methodological guidelines ensuring progress in science
- It is essential for scientific progress that anything is permitted: ‘anything goes’
-> you need a toolbox full of different kinds of tools, not only a hammer and pins.
wat deed Lakatos
tried to save the rationality of science from both Kuhns relativism and Feyerabends anarchism. He combines normative elements of popper and descriptive elements of kuhns philosophy
want het leek net alsof er geen regels mochten zijn door Kuhn & Feyerabends
wat zei lakatos over falsificationism
- direct falsification will be very rare, often researchers do not want to give up their theories that easily.
- but, when they have a better theory, they will switch.
- therefore there is still a role for falsification as demarcation, but it is not a descriptive principle
- if something is really not falsifiable, it should not be in science. but if it is, does not mean that it is a good theory
- paradigm and research programme can exist next to each other
wat heeft een theory volgens lakatos
- a core
- body of beliefs
- negative heuristics
- positive heuristic
body of beliefs =
beliefs that help the theory (=auxillary assumptions)
wat correspondeert met de duhem quine thesis
auxillary assumptions
negative heuristic
- you can never change the core, if you change the core you have to falsify the theory
- you can change the body of beliefs around it
voorbeeld van general intelligence
core: g exists
assumptions: unidimensional, latent, etc
progressive research programmes kenmerken
- growth
- new techniques
- more facts
degenerative research programmes
- shrinkage
- no new techniques
- no increase in facts
normative component of Lakatos=
a rational scientist should stick with a progressive programme, but abandon a degenerative programme
- Popper formulates the falsification criterion
- Avoids the induction problem and solves the demarcation problem better than the logical positivists
- Problems for falsification lie in the Duhem-Quine thesis and that falsificationism provides a poor description of scientific practice
- Kuhn argues that scientific revolutions imply shifts in meaning: successive theories are concerned with something different
- Feyerabend argues that strict norms are in the way of scientific progress, it is essential for scientific progress that “anything goes”
- Lakatos formulates the sophisticated falsificationism to save the rationality in science and brings back a normative component in his descriptive analysis
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