Philosophy of Science

1. Philosophy of Science Class 7

2. Admin… • Want to move my office hours tomorrow to 4:00-5:00. If you were already planning to come between 5:30 and 6:30, let me know. • Can you e-mail Assignments? Generally, no (class too big!). Yes, if you are having printing problems- follow up with a hard-copy a.s.a.p (I will do a quick compare). • Test- 30%,30% or 20%, 40%

3. Review of Dates • March 15- hand in outline/summary. You can use the drop box (special d.b. hours) • March 16- outline/summary pick up (office hours), • March 22- Final Test, outline/summary pick up • March 29- Hand in Rough Draft • April 2 (Friday)- pick up Rough Drafts (office) • April 5, pick up Rough Drafts (class) • April 8th- Final Draft Due- drop box

4. Quick Review of Last Class…

5. Good theories have… • Testability in principle • Explanatory power • Deepens and Broadens understanding • Predicts new phenomena (Used currently by scientists to accept or reject theories)

6. August Comte and Positivism (1798-1857)

7. A ‘Grown Up’ Science • Science is limited to the observable and therefore • Science should stick with what it is good at- observation and generalization! (You can probably see that Comte was a big fan of Bacon and Hume)

8. The Logical Positivists

9. Logical Positivists • Do theoretical entities really exist? • Vs • What do theoretical terms mean?

10. Verificationism • “the meaning of any statement is its method of verification” • My blue ball bounces = • If I drop this blue ball on the floor it will rebound back upwards once it has hit the floor

11. Operationalism • Just a further refinement of verificationism… • X is p means if O is performed on x then R • The blue ball is bouncy = • The blue ball is bouncy means if I throw the blue ball at the floor from height y and with motion x and observe its trajectory then I will observer that it will come immediately back up off the floor to a height z

12. The Ceteris Paribus Problem (All things being equal)

13. The problem of material implication (the if…then problem)

14. Truth Tables

15. Truth Tables

16. Happy Logicians • Generalized from actual examples of English • But then defined to be true • A nice precise system. • Or is it?

17. If then statement

18. Lets check our intuitions with a poll… (first, write down what you think)

19. More intuition checking…

20. Some Problems… • Particular instances don’t seem adequate to completely verify the if then statement. • It seems strange to put unrelated sentences in an if then statement and give it causal power. • The last two lines of the truth table seem very ad hoc and unintuitive

21. The logicians must make a decision… (Studies in Logic,. Charles Pierce, 1883,Tractatus Logico-Philosophicus- Wittgenstein, 1921) Remember- it’s a definition!

22. Side note • In case you think this is some strange philosophical move that demonstrates the silliness of philosophers… • Mathematicians make moves like this in math, too (e.g. negative numbers)… • It is a problematic consequence of wanting to have consistent, rigorous systems.

23. x is fragile = If (x is dropped on the floor) then (x will be destroyed) Problem: The fragile sock problem: A dog grabs the sock before it can hit the floor- and eats it…

24. Carnap’s Correspondence Rule Patch • Carnap (1891-1970) • Carnap’s patch: iff • If O is performed on x, then (x is p iff R) • If x is brought near the leaf microscope at time t) then (x is (electrically charged) iff (the leaves of the electroscope diverge). • (Note: iff = ‘if and only if’)

25. Pros and Cons • Removes the problem of Material Implication- Yay! Definitions work again. • The term of interest, p, is now buried: • If O is performed on x, then (x is p iff R)

26. Are these really serious problems? • Remember: • Philosophers want their theories to work with logic all the time- they must be foolproof! • Philosophy isn’t about ignoring problems ‘because they are too small’ • The logical positivists wanted their theory to be solid and ‘nit-pick’ free.

27. Logical Positivism- still popular! • Why? Well… • Can you think of any alternatives to trying to define theoretical terms? • (Maybe Atomism vs. Holism…Hempel’s network theory of meaning)

28. Review- Some possible test questions • Hume, Experiments • What was Hume’s argument? Why do you think philosophers took it so seriously? Why Was Hume’s argument relevant to science? Define causation. What role does it play in science? How have scientists responded to Hume’s problem? • Why did scientists devise experiments? What are the important components of experiments? What do experimental methods give science? Explain how problems like Hume’s led to experiments. List four ways in which induction can go wrong How do experiments prevent science from falling into these traps? • Devise an experiment. Discuss how your experiment is or is not vulnerable to Hume’s argument. As a scientist, what do you think you would do about this?

29. Review, Cont. • Theories, Comte, Logical Positivists • Consider the following theory. Explain why it is a good or bad theory (Hung’s list…) . • Why was Comte studying the history of science? How did Comte describe the theoretical stage of science? What was the connection between Comte and the Logical Positivists? What is you opinion of Comte’s Theory • List the three stages that the logical positivists’ definitions went through.Why did they change? Create a definition for: Eggs are fragile for each of these. What are some problems you might run into applying these definitions? • What were some issues that the Logical Positivists faced? How did they deal with these issues? Where do the Logical Positivists stand today?

30. Current state of philosophy of science (and science) • Modern way to define theoretical terms: • Provided by the Logical Positivists • Still used- e.g. psychology, operationalization • Memory=performance on flash card test • Modern method for doing research: • How are scientists doing science these days? • Popper!

31. Karl Popper1902-1994 Popper wanted to know: • What is good science? • How should we decide what is and what is not science?

32. To put it another way… • When should something be considered ‘scientific’? • Can science find out the truth about everything? • What is the scope of science? • Should science be able to study everything? • Should some topics be excluded from science? • What does it mean if something can’t be studied by science? If not, why not? • When is an activity scientific? • When is scientific activity ‘good science’? When is it ‘bad science’? • How should science be done? • What should we expect from science?

33. Some attempts to answer these questions • Bacon: Science should use my method. My method results in good science (because my method is objective) • Comte: Science should restrict itself to making generalizations from observations. Anything outside of this is outside bad science. • Logical Positivists: Science can study everything that is worth studying. Anything that science can’t define through verification is meaningless.

34. Popper’s Concerns • Increasing strangeness of scientific theories (e.g. quantum physics) • Dubious credentials of some theories claiming to be scientific (e.g. Freudian psychoanalysis, Marxism)

35. Why did Popper Care? • Science is supposed to be about the truth (about objective reality)! • Bad science is less likely to find the truth. • Science has a certain status that could be misused.

36. Popper’s proposed argument • All good science is like x (i.e. has the property x) • Your theory or story or explanation is not like x • --------- • Your theory is not good science!

37. Popper’s Proposed Argument, more detailed • All good science follows methodology x • Your ‘science’ does not follow methodology x • ------ • Your science is not good science.

38. Popper and Induction INDUCTION

39. The challenge • Getting rid of induction! • Aristotle said it could not be done! • The Medieval Natural Philosophers couldn’t do it! • Hume couldn’t do it! • Can Popper do it?

40. Popper’s Bright Idea • Swan x is white • Swan y is white • Swan z is white • ----------- • All swans are white. It seems fairly easy to determine the falsity of this statement…

41. Popper’s Method • 1. Find a hypothesis (from somewhere, somehow).This hypothesis must be falsifiable. (Note: theory) • 2. Using deductive logic, derive an empirical implication that proves the hypothesis to be false ( like indirect tests) • 3. Test the implication in some way-to see if it (the implication, not the hypothesis) is true or false. • 4. a)If the test shows that the implication is true, discard the hypothesis and go to 1. • b) If the test does shows the implication to be false, go back to step 2. • Popper called this the hypothetico-deductive method.

42. Seems like backward science! • Example: • Hypothesis: Apples fall to the ground • If it is false that [apples fall to the ground] • Implication: We should expect to see an apple hover in the air when released. • If we carry out the test, the implication is falsified. • Therefore we go back to step two and derive another implication

43. Some important features of Popper’s method • it makes falsification the main activity of science (black swan detector) • the more tests a hypothesis passes, the more corroborated it is. • science should progress by accumulating corroborated theories (i.e. hypotheses), while always being on the lookout for tests that might falsify these statements.

44. What counts as science • All good science follows methodology x • Your ‘science’ does not follow methodology x • ------ • Your science is not good science. • Methodological failure: If there appears to be no possible test that would prove the statement false, then that statement cannot be investigated by science.

45. Consider the following statements • I like bananas or I don’t like bananas. • Apples are a healthy snack. • The acceleration of gravity is 9.8 m/s2. • God is good. • The id controls your subconscious behaviours.

46. Metaphysics • Popper describes theories that cannot be investigated by science as being metaphysical. • Popper does not judge metaphysical theories. He does not, for example, say that they are morally wrong, or meaningless. • Popper simply says that metaphysical theories cannot be evaluated by scientific criteria. • Some other method of evaluation would need to be found if they were to be evaluated.

47. Group Discussion • If you were in charge of training a group of new scientists, would you pick Bacon’s method or Popper’s ( or do something different)? • On the board: • Which would you pick (or what would you do)? • One sentence stating why.

48. Popper and the Logical Positivists Different • Popper is interested in falsification, while the logical positivists’ theory depends on the idea of verification • logical positivism is concerned with meaning. Popper’s theory does not involve philosophy of language or the meaning of statements. • Popper was much less critical of ‘metaphysical theories’ than logical positivists

49. Popper and the Logical Positivists • The same: • Popper did think that observational statements were important, and could provide the basis for scientific theories. • Popper wasn’t too concerned with the discovery of hypotheses. What was important was how hypotheses were (or were not) justified. • Both Popper and the Logical Positivists took Hume seriously.

50. Problems with Popper? • 1. Find a hypothesis (from somewhere, somehow).This hypothesis must be falsifiable. (Note: theory) • 2. Using deductive logic, derive an empirical implication that proves the hypothesis to be false ( like indirect tests) • 3. Test the implication in some way-to see if it (the implication, not the hypothesis) is true or false. • 4. a)If the test shows that the implication is true, discard the hypothesis and go to 1. • b) If the test does shows the implication to be false, go back to step 2.