F34PPP Lecture 3: Vive la Revolution? Philip Moriarty School of Physics & Astronomy philip.moriarty@nottingham.ac.uk @Moriarty2112 www.nottingham.ac.uk/physics/research/nano

Suggested blog post topics [300 – 500 words, 10%] 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? Are prizes like the Longitude Prize the future of research funding? Can science be crowd-funded? Is peer review working? Should universities cut back on funding of PhD positions? Is Richard Dawkins closed-minded?

Last time… Bacon’s inductivism Idols of the Mind & Millikan’s manipulation “There’s nothing that’s scientifically proven”

Back to Bacon…

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.

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.”

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…

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?

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]

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.

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]

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

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

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

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

Popper and Falsification

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?

Popper and Falsification Bacon/ induction Popper

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

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

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.