1. Karl Popper Popper replaces induction with falsification
Science is not distinguished from non-science on basis of methodology. No unique methodology specific to science
Science consists mostly of problem solving.

2. Karl Popper All observations are selective and theory laden
A demarcation between science and pseudo-science is established by falsification. A theory is scientific only if it is refutable by a conceivable event
Every genuine test of a scientific theory is based on an asymmetry between verification and falsification

3. Sir Karl Popper ( )
Falsification is the idea that science advances by unjustified, exaggerated guesses followed by unstinting criticism.
Any "positive support" for theories is both unobtainable and superfluous; all we can and need do is create theories and eliminate error
Scientists never actually use induction. It is impossible to verify propositions by reference to experience

4. Falsificationism (1) Scientific Method Is there a scientific method?
What justifies scientific claims to knowledge?
Can we distinguish scientific method from non-scientific ways of thinking? (demarcation)
Does science progress?

5. Falsificationism (1) Falsificationism ‘No criterion of truth’:
Two Arguments:
No Theory/observation distinction:
‘Here is a glass of water’ is theory laden
In accepting the statement we must accept a significant amount of theory
We have only as much justification for accepting the observation statement as we do for the theory

6. Falsificationism (1) We can’t!
Falsificationism ‘No criterion of truth’:
Two Arguments:
No Theory/observation distinction:
Upshot: we cannot use observation to establish the truth of a theory
How can we establish the truth of scientific theories?
We can’t!

7. Falsificationism (1) Confirmation and Pseudoscience
Good scientific practice:
E.g. Einstein’s general relativity
Conjecture: mass of the sun bends the path of light
Apparent location
Actual location
moon

8. Falsificationism (1) Confirmation and Pseudoscience
Good scientific practice:
E.g. Einstein’s general relativity
Conjecture: mass of the sun bends the path of light
If the apparent location of the observed star doesn’t shift, the theory is wrong.
It will have been refuted.
The mark of a scientific theory is whether it can be falsified by observation

9. Falsificationism (1) Conjecture and Refutation:
“Falsificationists… prefer an attempt to solve an interesting problem by a bold conjecture, even (and especially) if it soon turns out to be false, to any recital of a sequence of irrelevant truisms” (CR: 231)
This gives us:
(i) a glimpse of scientific method
(ii) a demarcation criterion for science

10. Falsificationism (1) Scientific method:
Scientific theories have deductive consequences
They can be falsified but not confirmed.
The objective of scientific theorizing is to put forward (bold) hypotheses and then test them in order to falsify them
Theories are falsified by basic statements
(what is a basic statement?)

11. Falsificationism (1) Demarcation:
Scientific theories are those that can be falsified by basic statements.
Good scientific theories do not make themselves immune from falsification by use of ad hoc hypotheses

12. Falsificationism (1) Progress of Science:
Science progresses by eliminating theories that have been falsified?
But does it progress?
A scientific theory cannot be shown to be true. But some scientific theories do have varying degrees of success. They resist falsification.

13. Falsificationism (1)
“We must not look upon science as a body of ‘knowledge’, but rather as a system of hypotheses which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know that they are ‘true’, or ‘more or less certain’ or even ‘probable’

14. Kuhn (1) Thomas Kuhn (1922-1996) The Copernican Revolution (1957)
The Structure of Scientific Revolutions (1962)
History of science not compatible with rationalist view
Progress of science not cumulative, driven by the application of a method

15. Kuhn (1) Thomas Kuhn (1922-1996) The Copernican Revolution (1957)
The Structure of Scientific Revolutions (1962)
No obvious science/non-science demarcation
No context of discovery/context of justification distinction

16. Kuhn (1) Kuhn’s History of Science Two projects:
Descriptive — what is the structure of scientific history?
Normal science Scientific revolution
Explanatory — why does the history of science have this structure?
Paradigms

17. Kuhn (1) 1. Kuhn’s History of Science Descriptive Project:
Immature Science
Revolution
Normal Science
Crisis
Anomalies

18. Paradigm Diagram old paradigm unexplained observations competing new
paradigms
incommensurate
puzzle solving
one dominant paradigm
Mopping up operation
unsolved puzzles ignored
unexplained observations
unexplained observations and alternative interpretation ignored until enough accumulates to overturn current paradigm

19. Kuhn (1) 1. Kuhn’s History of Science Immature Science:
No prevailing school of thought
Various disparate theories
Competition

20. Kuhn (1) 1. Kuhn’s History of Science Normal Science: Stability
Determination of significant facts
Matching facts with theories
Articulation of theories (refinement and extension)
“puzzle -solving” neither tests nor confirms its theories

21. Kuhn (1) 1. Kuhn’s History of Science Normal Science:
Driven by a paradigm (more later):
Commonly held set of beliefs, procedures, techniques
Agreement upon questions of import
Agreement on what counts as a solution
Agreement upon standards of evaluation

22. Kuhn (1) 1. Kuhn’s History of Science Anomalies:
Not all expectations are borne out
Some anomalies lead to further discoveries (e.g. orbit of Uranus)
Some simply ignored
Troublesome anomalies
Challenge key theoretical concepts
Resist solutions
Inhibit application of theory

23. Kuhn (1) 1. Kuhn’s History of Science Crisis:
Weight of accumulated anomalies
No agreement on how anomalies are to be dealt with
Doubts arise

24. Kuhn (1) 1. Kuhn’s History of Science Revolution:
A new paradigm emerges
Old Theory: well established, many followers, politically powerful, well understood, many anomalies
New Theory: few followers, untested, new concepts/techniques, accounts for anomalies, asks new questions

25. Kuhn (1) 1. Kuhn’s History of Science Revolution:
A new paradigm emerges
Are old and new theories compared by some rational procedure?
“A new scientific theory 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” (Planck)

26. Kuhn (1) Scientific Revolutions The Ptolemaic model
The earth is at the centre of the planetary system
Problem:
How to explain the retrograde motion of planets

27. Kuhn (1) Scientific Revolutions
The Ptolemaic model
The earth is at the centre of the planetary system
Problem:
How to explain the retrograde motion of planets
Deferent
Earth
Planet
Epicycle

28. Kuhn (1) Scientific Revolutions
The Ptolemaic model
The earth is at the centre of the planetary system

29. Kuhn (1) Scientific Revolutions The Ptolemaic Model: Problems:
Complexity: epicycle upon epicycle
The accumulation of anomalies
No clear way forward

30. Kuhn (1) Scientific Revolutions The Copernican model
The sun is at the centre of the planetary system
Problem:
How to explain the retrograde motion of planets

31. Kuhn (1) Scientific Revolutions The Copernican model
The sun is at the centre of the solar system

32. Kuhn (1) Scientific Revolutions
The Copernican Revolution was not the consequence of an old theory with less ‘empirical content’ being replaced by a new theory with more
No appeal to reason alone
‘propaganda’
To discover how scientific revolutions are effected, we shall therefore have to examine … the techniques of persuasive argumentation within the quite special groups that constitute the community of scientists (SSR: 94)

33. Kuhn (1) 2. Explanatory Project Two Questions:
If this is the course of the history of science, why?
Why aren’t competing theories/traditions measured against each other by some rational procedure?

34. Kuhn (1) 2. Explanatory Project Paradigms Disciplinary Matrix:
(i) Symbolic generalisations
(ii) Metaphysical commitments
(iii) Scientific values
(iv) Heuristic models
(v) Exemplars

35. Kuhn (1) Explanatory Project Why is normal science stable?
It is conducted wholly within the terms of a disciplinary matrix:
questions
procedures
problems
priorities
standards of evaluation
All are generated by the disciplinary matrix

36. Kuhn (1) Explanatory Project Why is theory change revolutionary?
Theory change is brought about by a ‘gestalt switch’ a complete change of world view
There is no neutral point from which one can assess theories from two paradigms simultaneously