1. Science & Its Pretenders
Cf. Reading List for core and suggested readings.

2. Topics The Amazing Power of Science – A Very Brief Reflection
Science & Pseudoscience – Popper’s Demarcation Criterion
Comments on Popper’s Falsificationism
Hypothesis & Evidence
Criteria of Adequacy
Further Example: Evolution vs. Creationism

3. The Amazing Power of Science – A Very Brief Reflection
Influence every aspect of our lives tremendously.
Change the world with an exceedingly fast pace.
Produce scientific knowledge with astounding breath and depth.

4. Science & Pseudoscience – Popper’s Demarcation Criterion
About 100 yrs ago, people were deeply interested in theories like:
Alfred Adler’s ( ) individual psychology:
An inborn sense of inferiority
Strive for superiority
Seemed to be able to explain everything within its field of inquiry!

5. Albert Einstein’s (1879-1955) theory of relativity:
Relativistic spacetime e.g. simultaneity is relative.
E = mc2
One of the two pillars of modern physics.

6. Both claimed to be “scientific”.
“Science” signifies __________, ___________, ___________.
Yet, Karl Popper ( ) held that theories like Alder’s is actually not scientific.

7. He raised the demarcation problem:
When should a theory be ranked as scientific?
Is there a criterion for the scientific status of a theory?
Scientific / Pseudoscientific

8. His criticism of theories like Adler’s:
Adler’s theory could easily “explain” two “diametrically opposite” cases, e.g.:
A man pushes a child into the water with the intention of drowning it.
A man sacrifices his life in an attempt to save the child.
How?
By appealing to the idea of inferiority feeling, . . .

9. Its “explanatory power” is just a disguise of its “interpreting power”.
Points for analysis in your paper, e.g.: How is this interpreting power harmful to a theory? (Hint: meaning shift of some key concepts)
This apparent strength - capable of explaining everything - is in fact a weakness.

10. Arthur Eddington’s confirmation (1919) of Einstein’s theory was different:
The light-bending prediction
Might be refuted — not always confirmatory!

11. Consequently, Popper proposed:
The criterion of the scientific status of a theory is its
falsifiability,
or refutability,
or testability.
Is this criterion adequate?

12. Comments on Popper’s Falsificationism
Two senses of falsifiability:
Falsifiability as a logical property of statements
Falsifiable, e.g.:
“It never rains on Wednesdays.”
“All substances expand when heated.”

13. But both these senses are problematic!
Unfalsifiable, e.g.:
“Luck is possible in sporting speculation.”
“There is a ghost in this room which cannot be sensed, directly or indirectly.”
Falsifiability as a methodological prescription of how scientists should act
E.g. try to make “all substances expand when heated” unfalsifiable in this sense.
But both these senses are problematic!

14. 1. The logical sense Too _______
Suppose T is a theory having testable predictions.
Let C be, say, “there is a ghost in this room which cannot be sensed, directly or indirectly”.
Then T & C has testable predictions and thus scientific in the logical sense!

15. 2. The methodological sense
Too ________
E.g. the discovery of Neptune
Newton’s theory of gravitation wrongly predicted the orbit of Uranus – abandoned it?
In fact, some scientists tried to rescue Newton’s theory by postulating the existence of an unknown planet.
Neptune was finally discovered at almost the exact place and time as predicted.

17. The “failure” of Popper's criterion throws up an important question:
Is it possible to find some common features shared by all the sciences, but not shared by anything else?
Has science “essential features”?
Popper assumed that the answer was yes.

18. Ludwig Wittgenstein (1889-1951) argued against essentialism.
Family resemblance concepts like “game” have no essential features.
Cf. His Philosophical Investigations, sections 66-7.

19. GAMES
A B C D E F
FEATURES

20. The same may be true of “science”.
Note the heterogeneity of science.
If so, no simple criterion for demarcating science from pseudoscience.
How actually should we choose among hypotheses – scientific or pseudoscientific?

21. (+ background assumptions)
Hypothesis & Evidence
The logic of hypothesis testing:
Main hypothesis
(+ background assumptions) I1 I2 I3
deduction
induction

22. Discussion - a daily example:
The problem:
A lamp does not light up.
Hypothesis:
Implication:
Test:
Result:

23. Positive evidence does not prove conclusively that a hypothesis is correct.
There are always competing hypotheses that have the same set of positive evidence. I1 I2 I3 H In I1 I2 I3 H’ In

24. Negative evidence does not prove conclusively that a hypothesis is incorrect.
A Modus Tollens:
(Hypothesis H • Assumptions A)  Implication I
 I
 (H • A)
So maybe the trouble comes from A.

25. Example:
Columbus and the negative evidence against the flat Earth hypothesis
Supporting the round Earth hypothesis:

26. Facts alone cannot decide which hypothesis to accept.
Saving the flat Earth hypothesis:
Assumption: light travels in curved lines.
Facts alone cannot decide which hypothesis to accept.
Criteria of Adequacy are needed.

27. Discussion:
What do you think are the criteria of adequacy?