The role of Experiment in scientific research

1. The role of Experiment in scientific research Mikkel Willum Johansen willum@math.ku.dk

2. Absolute truth Karl Popper’s picture of scientific development Scientific theories Time The role of the experiment • Two different roles • Creation of phenomena (Ian Hacking) • Testing of theory • The hypothetico-deductive method • State a theory (a bold hypothesis) • Deduce empirically testable consequences • Conduct the test(s) • Adjust, if your hypothesis is falsified

3. Parallax Brahes and the parallax

4. The Earth doesn’t revolve around the Sun Brahes and the parallax • Brahes argument • If the Earth revolves around the Sun, it must be possible to observe a parallax with my instruments • It isn’t possible to observe a parallax

5. At least one of the hypothesis above must be false Brahes and the parallax • Brahes argument • If … • … the Earth revolves around the Sun • … the Stars stand still • … light travels in straight lines • … the Universe is not ridiculously big • … • … • … thenit must be possible to observe a parallax with my instruments • 2. It isn’t possible to observe a parallax

6. The web of beliefs “The totality of our so-called knowledge … is a man-made fabric which impinges on experience only along the edges ... A conflict with experience at the periphery occasions readjustments in the interior of the field. Truth values have to be redistributed over some of our statements. Reëvaluation of some statements entails reëvaluation of others, because of their logical interconnections … But the total field is so underdetermined by its boundary conditions, experience, that there is much latitude of choice as to what statements to reëvaluate in the light of any single contrary experience.” (Willard V. O. Quine: ”Two Dogmas of Empiricism”, 1951) Quine (1908-2000)

7. Experimenters regress Experiments only tell us something, if they are done competently, but when is that? In training: When we get the right result In real time science: ? To know the right answer, we must make successful experiments, but to know whether an experimentsis successful or not, we most know the right answer

8. Planarian Edible knowledge Period: Late 1950s to mid-1970s Main figures: James McConnell and George Ungar McConnell’s experiment:

9. Edible knowledge Period: Late 1950s to mid-1970s Main figures: James McConnell and George Ungar McConnell’s experiment:

10. Edible knowledge Period: Late 1950s to mid-1970s Main figures: James McConnell and George Ungar McConnell’s experiment: - +

11. Edible knowledge Period: Late 1950s to mid-1970s Main figures: James McConnell and George Ungar McConnell’s experiment:

12. Trained worm Edible knowledge Period: Late 1950s to mid-1970s Main figures: James McConnell and George Ungar McConnell’s experiment: The 1962 result When trained worms are fed to untrained, the untrained worms become 1.5 times more likely to respond to light

13. Edible knowledge – the controversy • Experimenter’s regress • It is unknown which factors might • influence the experiment => • It is unknown what constitutes a succesfull experiment • Which variables are important for the experiment? • Slime • Treatment of the worms • Species and size of the worms • Housing (dark or light?) • Nature of the electric shock • Barometric pressure • Skilled practice (golden hands)

14. Edible knowledge – the controversy (Collins & Pinch p. 16)

15. Scientific controversy • Scientists reasons for believing or disbelieving a • controversial experiment (based on interviews) • Faith in a scientist’s experimental capabilities and honesty, based on previous working partnership • The personality and intelligence of experimenters • A scientist’s reputation gained in running a huge lab • Whether or not the scientist is worked in industry or academia • A scientist’s previous history of failures • Inside information • Scientists’ style and presentation of results • Scientists’ psychological approach to experiment • The size and prestige of the scientist’s university of origin • The scientist’s integration into various scientific networks • The scientists nationality • (Collins and Pinch, p. 101)

18. James McConnell’s The Worm Re-Turns: The Best of from the Worm Runner’s Digest p.11

19. (Collins & Pinch p. 17)

20. Absolute truth Scientific theories Time Perspectives and conclusion • The Hypothetico-deductive method • State a theory (a bold hypothesis) • Deduce empirically testable consequences • Conduct the test(s) • Adjust, if your hypothesis is falsified Karl Popper’s picture of scientific development

21. Perspectives and conclusion Experimenters regress To know the right answer, we must make successful experiments, but to know whether an experimentsis successful or not, we most know the right answer • Perspectives • What happens when commercial interests enters the debate? • When are scientists dishonest? • Uncertainty

22. Perspectives and conclusion ”The aim of this book is to explain the golem that is science. We aim to show that it is not an evil creature but it is a little daft. Goem Sceince is not to be blamed for its mistakes; they are our mistakes. A gollem cannot blamed if it is doing its best. But we must not expect too much. A golem, powerful though it is, is the creature of our art and our craft.” (Collins & Pinch, p. 2)