Understanding Science 11. Special Pleading © Colin Frayn,

Introduction Special pleading is the last resort “But what if… ?” Defending paranormal claims: –The tooth fairy –Father Christmas –Carl Sagan’s Dragon "Introducing an unsupported, speculative claim in order to justify a theory without any rigorous evidential support" © Colin Frayn,

Paranormal Claims Paranormal Claimants are never able to prove their abilities under laboratory conditions “My powers don’t work in the presence of skeptics” –This is easily testable, of course “My powers don’t work when they are being tested” –They work just fine when you’re performing to an audience, and that is a test. –What about historical analysis? –What about video /audio recordings? © Colin Frayn,

Dowsing Attempting to locate certain substances at a distance without a line-of-sight –Often used to find water –Dowsers are almost all genuinely convinced in their alleged abilities Confirmation bias helps to fuel this In reality, caused by the Ideomotor Effect –Small unconscious movements cause large effects –This is well studied and understood Excuses usually involve “skeptics made me fail” –E.g. “Negative energy disrupts my powers” –Even if the powers work perfectly on a non-blinded test –Denial is pretty much universal, even after disproof They value anecdotes above good quality evidence These alleged powers are an important part of their lives © Colin Frayn,

Young-Earth Creationism “The Earth is less than 10,000 years old” –(Real age = 4.54 Billion years) An argument based entirely on ignorance and special pleading Radiometric dating: –Used to date old samples –Different elements with different decay rates can probe different timescales Special pleading: –“The conditions may not have been what we expected” –“The decay rate may have changed” –“The physics of radioactive decay may have changed” © Colin Frayn,

Conspiracy Theories All conspiracy theories are wrong! 9/11 deniers –Official explanation is perfectly sufficient –Conspiracy requires utterly silent conspirators –“Everyone’s in on it” Expanding group of conspirators (1,000s) Highly implausible No evidence whatsoever for this “The lack of evidence for the conspiracy is evidence for the conspiracy” –Commonly used in conspiracy theories –Flags a person as unwilling to engage in rational thought © Colin Frayn,

The Scientific Response Compare with “infinite free energy” claim –We’re not convinced by claims stated without evidence –… especially if they go against the laws of physics Logical Proof vs. Empirical Proof –Logical proof is rarely found in science It’s the realm of mathematics and philosophy –Science deals with empirical proofs Forming hypotheses, testing hypotheses through observation –Science can rarely prove anything 100% false So there’s always room for a “but what if?” scenario A tiny slither away from the “definitely false” end of the spectrum of certainty © Colin Frayn,

Counter Arrguments Doesn’t Science use special pleading? –Sort of, in some cases –Special pleading is a process used to introduce possibilities for later investigation –Speculation is part of science We need hypotheses to test … but we do have to test them first before accepting them –Speculations are not scientific theories They must be proved first, using evidence –A speculation is always inferior to any hypothesis supported by evidence Remember to consider the Bayesian prior! A plausible speculation is useful for directing thought … but is not evidence © Colin Frayn,

Summary Special pleading involves –introducing a speculative claim –without evidential support It can rescue an argument from logical impossibility –… but that’s not much of a claim! Make sure you don’t fall for this yourself –It’s always best to admit what you don’t know –Ignorance is not a vice –Don’t hold on to beliefs just because you want them to be true It’s always best to believe as many truths, and discard as many falsehoods, as possible © Colin Frayn,