Understanding Science 14. Skepticism © Colin Frayn,

Introduction “Scientific Skepticism is the application of best practices to knowledge acquisition” Don’t base your beliefs on emotions, but on facts 1.Truth is important 2.Human perception is often unreliable 3.Use all of our knowledge 4.Use the Scientific method for investigating empirical claims © Colin Frayn,

Historical Skepticism Ancient Greece, ~300BCE –There is no absolute knowledge –All proofs are founded on other proofs so cannot be relied on René Descartes ( ) –“I think therefore I am”! –The one thing that cannot be doubted is my own existence. The Matrix –Is our entire perception constructed and unreal? –How can we tell that we are not in a Matrix? We can’t! © Colin Frayn,

Scientific Skepticism Extending the Skeptic tradition 1.Our senses genuinely tell us something useful about the real world –We must assume this to make progress. –We can then learn how our senses deceive us. –The fact that we are making progress suggests that it’s a sensible assumption. 2.The laws of science are constant in time and space –Astronomy / cosmology – looking at things far away and a long time ago. –Can check that the laws of physics appear constant. E.g. spectra, supernova, Cosmic Microwave Background etc. –So far we have no reason to believe that this isn’t true. © Colin Frayn,

Skepticism, Gullibility and Cynicism Gullibility – Being easy manipulated, overly trusting and not employing sensible filters to knowledge you hear. Credulousness – Willing to believe claims with insufficient evidence Cynicism – Being pessimistic about human nature, not trusting, expecting the worst. Closed-mindedness – Being unwilling to entertain new ideas. Dogmatic – Stubborn, clinging to specific ideas often in the face of evidence. © Colin Frayn, Gullibility Cynicism Skepticism

Why Skepticism? Mental Twister –Incompatible beliefs –In conflict with reality –Causes anxiety and stress –Leads to cognitive dissonance You can’t avoid reality –It’s best to choose beliefs that are in agreement with the real world –This minimises stress and anxiety –Make optimum use of all opportunities –Choose beliefs that are supportive and accurate! © Colin Frayn,

The Main Lesson Nothing in Science is permanent –We choose the best explanation for now –That explanation may change later – that’s ok! Einstein’s Cosmological Constant –Like a pressure holding the Universe apart –Rejected when the Universe was shown to be expanding –Brought back in the late 1990s when measurements showed that the expansion was accelerating Magic shows –Magicians know exactly how to trick us –They’re not the only ones –Our brains take short cuts which can be exploited Sometimes by accident –Understanding those weaknesses makes better at avoiding these exploits Lack of skeptical thinking causes much pain and suffering © Colin Frayn,

Educating Newton Isaac Newton ( ) Possibly the greatest scientist ever What would he make of modern science? –Could you explain it to him? –How did Science come about? Free book available for download © Colin Frayn,

Review 1.Proof 2.Bayes’ Theorem 3.The Scientific Method 4.Pseudoscience 5.The Burden of Proof 6.Conspiracy Theories 7.Intuition 8.Logical Fallacies 9.Science and Scientists 10.The Supernatural 11.Special Pleading 12.The Galileo Gambit 13.Significance 14.Skepticism © Colin Frayn,

Summary Please spread the word about these lectures Please download and read my book Constructive feedback gratefully received Suggested continued learning: –Podcast : The Skeptics Guide to the Universe –Book : Demon Haunted World (Carl Sagan) Thank you very much for listening! © Colin Frayn,