F34PPP Lecture 3: Vive la Revolution?

1. F34PPP Lecture 3: Vive la Revolution? Philip Moriarty School of Physics & Astronomy philip.moriarty@nottingham.ac.uk www.nottingham.ac.uk/physics/research/nano

2. F34PPP in brief -- assessment • A short blog post (300 - 500 words) [Deadline: Oct. 20 23:55] 10% • An opinion piece (along the lines of a one-page Physics World article, 1000-1500 words) [Deadline: Nov. 17] 30% • A "feature article" (2000-2500 words, in the style of a broadsheet article) [Deadline: Jan 12] 60%

3. Suggested blog post topics • Should scientists have to justify their research in terms of its socioeconomic impact? • Do social media have a role to play in the scientific process? • When should scientists “go public” with their results? • Should Google have sacked James Damore? • Is “many worlds”/multiverse theory science? • Can science be crowd-funded? • Is peer review working? • Should universities cut back on funding of PhD positions? • Is Richard Dawkins closed-minded?

4. Last time… • Bacon’s inductivism • Millikan’s manipulation • “There’s nothing that’s scientifically proven”

5. Back to Bacon…

6. The Idols of the Mind Idols of the Tribe – seeing order/patterns where there are none (cf “patternicity”); wishful thinking; jumping to conclusions. Idols of the Cave – personal/ideological preferences. Idols of the Marketplace – fallacies in reasoning due to jargon and language. (Nothing to do with markets in “free market” sense, but we’ll come back to that topic…) Idols of the Theatre – being wedded to a particular (philosophical) framework.

7. Bacon’s Inductivism - Observation followed by Induction. - Bacon argues that observation must be based on methods which minimise the influence of the four idols. - Generate set of observations. - Use these observations as basis of generalisations – scientific laws. (e.g. F=GmM/r2 , PV = nRT, Snell’s law etc..etc..) “Man, as the minister and interpreter of nature, is limited in act and understanding by his observation of the order of nature; neither his understanding nor his power extends further.”

8. Induction and Bacon • Induction: deductively invalid but persuasive argument. • Observation without bias or prejudice (!) • Instruments should eliminate the role of the “unreliable senses” • Induction (in sense Bacon used term) is generalisation from N cases to all cases…

9. Bacon’s Inductivism – Some problems • We don’t really do experiments with no preconceived ideas, do we? • Nor do we completely disregard expertise (Idol of the Theatre). Is science truly underpinned by a “belief in the ignorance of experts”? • ..and does Bacon’s inductivism actually work?

10. David Hume • An empiricist (along with Locke, Berkeley) • Argues that Bacon’s inductive reasoning is “not really reasoning at all, but rather merely a habit or a psychological tendency to form beliefs about what has not yet been observed on the basis of what has already been observed.” [Ladyman, p.40]

11. When the sun goes down… • …how do we know it will rise again tomorrow morning? • Logically possible that sun won’t rise tomorrow. • Justification for sun rising tomorrow (or ball falling to ground when dropped) is on basis of experience • But we assume that the future will be the same as the past • Justified by logic? No. Logically possible for future to be different from past.

12. David Hume • An empiricist (along with Locke, Berkeley) • Argues that Bacon’s inductive reasoning is “not really reasoning at all, but rather merely a habit or a psychological tendency to form beliefs about what has not yet been observed on the basis of what has already been observed.” [Ladyman, p.40] • “May we venture to hope that when Bacon's next centenary is celebrated the great work which he set going will be completed; and that Inductive Reasoning, which has long been the glory of Science, will have ceased to be the scandal of Philosophy?” [CD Broad, 1887 – 1971]

13. Inductive arguments “The very expression “scientifically proven” is a contradiction in terms. There’s nothing that is scientifically proven. The core of science is the deep awareness that we have wrong ideas, we have prejudices. …we have a vision of reality that is effective, it’s good, it’s the best we have found so far. It’s the most credible we have found so far; it’s mostly correct.” Carlo Rovelli http://www.newrepublic.com/article/118655/theoretical-phyisicist-explains-why-science-not-about-certainty

14. …but “mostly correct” can be more than good enough

16. The uniformity of nature • Hume: We assume the uniformity of nature • Can we prove this? • A “non-uniform” universe is conceivable • Case for uniformity rests on argument from induction • No logical/rational justification for uniformity? www.cafepress.com

17. “Whether this is something that should worry us, or shake our faith in science, is a difficult question that you should ponder for yourself”

18. Popper and Falsification

19. Popper and Falsification • Need an infinity of cases to definitively verify that a theory is correct – problem of induction • ..but one case can prove it wrong. • “All swans are white”. Hypothesis. Only one example required to prove it false – falsifiability. • One example?

20. Popper and Falsification Popper Bacon/ induction

21. Popper and Falsification • But this is not how lots of science (including physics!) is done. • We very often don’t start with a theory. X The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka!, but rather, “hmm…that’s funny” Issac Asimov

22. More problems with Popper • How do we know we’ve falsified a theory? Could our experimental measurement/observation be flawed?

23. More problems with Popper Popper’s “nihilism about induction” [Ladyman, p. 87] would mean that jumping out of a top-floor window is equally rational to taking the stairs.