Transcript Document

Thomas Kuhn (1922-1996)
Paradigms, normal science and
revolution
Zoltán Dienes, Philosophy of Psychology
Paradigm : The entire constellation of beliefs, values and techniques
shared by members of a scientific community.
(Includes: universally recognized scientific achievements that
provide model problems and solutions to a community of
practitioners. Hence the name “paradigm”)
E.g. Newtonian dynamics.
Paradigm : The entire constellation of beliefs, values and techniques
shared by members of a scientific community.
Example in Psychology:
Behaviourism:
An analysis of e.g. dogs salivating to a bell in terns of classical
conditioning provides a model problem and solution
Beliefs and values include:
Theories must only refer to stimuli and responses, not internal states;
all learning can be conceptualised as conditioning, etc
Normal science: research firmly based on such a paradigm (the
coming of maturity of a science)
Pre-normal science: there exists a range of different schools, not
united by a common paradigm
Normal science:
An attempt to force nature into the preformed and rigid box that the
paradigm provides. The aim is to stay within the box.
Kuhn:
Normal science is puzzle solving. If the puzzle is not solved, the
failure reflects on the scientist not on the paradigm.
The person who blames the paradigm will be seen as the carpenter
who blames his tools.
The man who succeeds proves himself an expert puzzle solver, and
the challenge of the puzzle is what drives him on.
Contrast Popper – experiments test theories not people
(Contrast Donovan, Laudan and Laudan, 1992)
Kuhn:
A common paradigm frees the scientific community from having to
constantly re-examine first principles;
community is free to concentrate exclusively on the subtlest and most
esoteric of phenomena that concern it
“To turn Sir Karl’s view on its head, it is precisely the abandonment of
critical discourse that marks the transition to a science”
Kuhn:
Failure with a new problem is disappointing but not surprising:
problems do not often yield to the first attack. Scientists do not
renounce the paradigm.
Difficult anomalies can be set aside for future work.
(It is OK to provisionally ignore an apparent falsification of your
favourite theory!)
The scientist who pauses to examine every anomaly he notes will
seldom get significant work done.
(Are anomalies simply ignored? Contrast Donovan et al)
Kuhn:
Crisis: build up of anomalies that resist solution. Creates a growing
sense that the paradigm has ceased to function adequately in the
exploration of nature.
Kuhn:
Crisis: build up of anomalies that resist solution. Creates a growing
sense that the paradigm has ceased to function adequately in the
exploration of nature.
Having achieved the status of a paradigm, a scientific theory is declared
invalid only if an alternative candidate is available to take its place.
“The methodological stereotype of falsification by direct comparison
with nature does not exist in actual science”
The decision to reject one paradigm is always simultaneously the
decision to accept another: a comparison between paradigms occurs.
(Do scientist only treat difficulties as acute if there is a rival? Contrast
Donovan et al)
Incommensurability between paradigms
Kuhn: There is a sense in which work in different paradigms cannot be
compared (or are difficult to compare).
1. Disagreement over the list of problems to be solved.
“What causes conscious awareness?”
“How fast can mental images be rotated?”
were not legitimate problems for behaviourists.
Information processing psychology de-emphasized learning;
connectionism brought it back to the fore
2. Disagreement over how to describe basic observations
A hypnotherapist might literally see a subject going into trance, while
an academic researcher might just see someone relaxing.
“Sam is an extrovert” means different things depending on your theory
of extroversion and how the extroversion scale was developed
The actual data are different when seen through the lense of
different paradigms.
Must they necessarily be?
Same theory of telescope could be used for providing data to test
big bang and steady state cosmology paradigms;
Same data on children’s reading errors can be used for testing
connectionist and information processing accounts of reading
Kuhn:
When two scientific schools disagree about
what are the problems
what counts as a solution
what the data actually are
they will talk past each other in debating their respective paradigms.
So how can one choose between different paradigms?
Kuhn:
When paradigms enter into a debate about paradigm choice, their role
is necessarily circular: Each groups uses its own paradigm to argue in
that paradigm’s defence.
The protagonists provide a clear exhibit of what scientific practice
will be like for those who adopt the new view of nature.
Kuhn:
Paradigm choice can never be settled by logic and experiment alone.
It is an act of faith: Despite all the problems a new paradigm
currently has, is it a way of practicing science that is likely to be
fruitful?
“In paradigm choice there is no standard higher than the assent of the
relevant community.”
Two different ways of practicing psychology:
Connectionism
Build a network to solve a learning
or constraint satisfaction problem:
How many layers? How
connected? What learning rule?
Two different ways of practicing psychology:
Connectionism
Build a network to solve a learning
or constraint satisfaction problem:
How many layers? How
connected? What learning rule?
Information processing psychology
Find experimental
dissociations to determine
how many boxes to draw
and how to connect them;
what rules transform
representations in each box
In 1980s when connectionism was taken up enthusiastically,
networks were shown to behave a little bit like people in e.g.
learning past tense of verbs
But many things they could not do
Fodor and Pylyshyn (1988) provided arguments that it was
impossible for them to do the things cognitive psychologists were
really interested in, like language
In 1980s when connectionism was taken up enthusiastically,
networks were shown to behave a little bit like people in e.g.
learning past tense of verbs
But many things they could not do
Fodor and Pylyshyn (1988) provided arguments that it was
impossible for them to do the things cognitive psychologists were
really interested in, like language
But many people started using networks, including to model
language: It was a way of practicing psychology that had promise.
Who knows how the arguments of Fodor and Pylyshyn would stand
the test of time.
Note information processing psychology had not solved the
problems of language either.
No logical argument for why a researcher must choose one or the
other
Kuhn:
To go between paradigms, cannot be done step by step; it happens
all at once like a Gestalt switch.
The transfer of allegiance from paradigm to paradigm is a
conversion experience.
Converting people is difficult. Typically new paradigms are
introduced by a person new to the field.
Max Planck: “A new scientific truth does not triumph by
convincing its opponents and making them see the light, but rather
because its opponents eventually die, and a new generation grows
up that is familiar with it”.
(Is that true?)
Kuhn:
Revolution: the change of a paradigm in a discipline
Revolution is a transformation of vision, crises are terminated not
be deliberation but by a gestalt switch.
After a revolution the data themselves change and the scientists
work in a different world.
Gestalt switch: the data changes
(Implications:
One way of looking at the data is not more true than another ?
One cannot simultaneously consider the data from the point of
view of two different theories ?)
Are there objective reasons for why scientists should favour one
theory over another?
Does science tend to move closer to the truth?
Do scientists try to falsify fundamental theories?