# Scientific Reasoning ### Dr. Joe Lau Philosophy Dept @ HKU Homepage: http://joelau.github.io Slides: https://hackmd.io/@joelau/2022-mao July 2022 HKU MAO Online Summer Programme --- ## Joe Lau 劉彥方 * BA (Oxford), PhD (MIT) * Department of Philosophy, HKU. * (2011) [*An Introduction to Critical Thinking and Creativity*](https://amzn.to/3ia362t). Wiley. * (2018) 《批判性思维与创造力》 学林出版社。 * (2021) [《哲食之道》](https://shop.oupchina.com.hk/collections/%E5%93%B2%E5%AD%B8-%E6%96%87%E5%AD%B8-1/products/9789888747948) 牛津大學出版社。 --- ## Introduction * What is scientific reasoning? * Reasoning used in scientific research. * Aim: Empirical theories and predictions. * Includes critical & creative thinking. * Not just for scientists! --- ## CT: Deductive logic * Validity / logical consequence * Romeo kissed Juliet. What follows *logically*? * Logic in maths, daily life. * See exercises. --- ## CT: Inductive reasoning * Romeo kissed Juliet. What is *probable*? * Probability and statistics. * Technical: Bayes theorem, t-test, ANOVA * "Probability is the very guide to life." --- ## 1. Correlation is not causation > Researchers at the Cleveland Clinic: Patients taking sildenafil have a 69% lower risk of developing Alzheimer's compared to non-users. --- ## Alternative explanations A correlates with B because: * C causes both A and B (breakfast & grades). * B causes A (self-esteem & depression). * ... * Just a coincidence. ---  --- ## 2. Importance of control * A → B. What if A is absent? * Vitamin C and recovery from flu. * Double-blind studies in medicine. --- ## Thinking about vaccines > The vaccine is useless because even if you have taken the vaccine you can still end up in the hospital. --- ## Personal experience vs statistics > I am not taking the vaccine. My friend's grandmother died after vaccination. --- ## Deng Xiaoping (1904-1997)  --- ### Which is more likely for an average Chinese citizen: Death from stomach cancer or traffic accident? --- ### Namibia is a country in Africa. Give an estimate of its population. Is your estimate above or below 100 million?  --- ## 3. Not easy to be objective * Cognitive biases: anchoring, confirmation bias, over-confidence ... * Psychologists: system 1 vs system 2 --- ### If it takes 5 machines 5 minutes to make 5 pots, how long would it take 100 machines to make 100 pots? * What is the answer? * What is the first answer that comes to mind? --- ## How to avoid biases? * Focus on the reasons * Gain more knowledge * Consider objections and counterexamples * Learn from good role models * Review your track record * Emotional maturity --- ## Who is this person? {%youtube ihaB8AFOhZo %} --- ## Russell's advice to 2959 >I should like to say two things, one intellectual and one moral. The intellectual thing I should want to say is this: --- > When you are studying any matter, ... Never let yourself be diverted either by what you wish to believe, or by what you think would have beneficent social effects if it were believed. But look only, and solely, at what are the facts. ... --- ## 4. Scientific mindset: ## Focus on the truth * Lots of misinformation, propaganda these days. * The truth can be hurtful, unpleasant. * Avoid wishful thinking, ...  --- # What happened in 1905? --- ## Einstein's *Annus Mirabilis* Four profound papers in 1905: * Photoelectric effect * Brownian motion * E=mc² * Special relativity --- ## Einstein on Hume (1711-1776) >Hume, whose *Treatise of Human Nature* I had studied avidly and with admiration shortly before discovering the theory of relativity. It is very possible that without these philosophical studies I would not have arrived at the solution. --- ## Einstein on philosophy >So many people today - and even professional scientists - seem to me like somebody who has seen thousands of trees but has never seen a forest. --- >A knowledge of the historic and philosophical background gives that kind of ***independence from prejudices*** of his generation from which most scientists are suffering. --- >This independence created by philosophical insight is - in my opinion - the mark of distinction between a mere artisan or specialist and a real seeker after truth. ---  --- ## 5. Be an independent thinker * Conformity is an enemy of truth and progress. * Creativity requires independent thinking. * Great ideas often began as heresies. * Truth over authority and tradition. * Critical thinking as mental firewall. --- ## Things to read * See Critical Thinking Web: http://philosophy.hku.hk/think --- ## Russell's second thing >The moral thing I should wish to say … I should say love is wise, hatred is foolish. In this world which is getting more closely interconnected we have to learn to tolerate each other, we have to learn to put up with the fact that some people say things that we don't like. --- >We can only live together in that way and if we are to live together and not die together we must learn a kind of charity and a kind of tolerance which is absolutely vital to the continuation of human life on this planet.