Pinker vs Popper

Steven Pinker has instructed twitter that Karl Popper is no good:

Most scientists cling to Karl Popper’s account of how science should work, but his falsification criterion isn’t so accurate (most papers don’t say “The data fail to falsify this theory”) and the Bayesian model of science is more general and accurate.

He links to a short blog post about Bayesian epistemology. Popper’s epistemology sez that scientific knowledge is created by conjecture and criticism. Scientists guess solutions to problems and eliminate those guesses by critical discussion that may include experiments. A theory is either right or wrong. If a scientist does an experiment and that experiment doesn’t contradict his theory, then  the theory may be right. If the scientist does the experiment and the result contradicts his theory then he has a problem: either the experiment is wrong or theory is wrong or both are wrong. And we decide whether to reject the theory or the experiment as a result of critical discussion as pointed by Popper in The Logic of Scientific Discovery, Section 29:

Every test of a theory, whether resulting in its corroboration or falsification, must stop at some basic statement or other which we decide to accept. If we do not come to any decision, and do not accept some basic statement or other, then the test will have led nowhere. But considered from a logical point of view, the situation is never such that it compels us to stop at this particular basic statement rather than at that, or else give up the test altogether. For any basic statement can again in its turn be subjected to tests, using as a touchstone any of the basic statements which can be deduced from it with the help of some theory, either the one under test, or another. This procedure has no natural end. Thus if the test is to lead us anywhere, nothing remains but to stop at some point or other and say that we are satisfied, for the time being. 

Pinker sez that scientists don’t write “The data fail to falsify this theory”. Earlier in the same tweet he sez that Popper’s ideas are about how science should work. Perhaps if scientists followed Popper’s advice they would make more progress. Pinker doesn’t make any argument against this possibility. His argument is like claiming that the existence of many obese persons refutes the notion that obesity is bad. Pinker himself hasn’t followed Popper’s advice to look for criticisms of his ideas. For example, Pinker accepts the results of twin experiments (The Blank Slate, Chapter 3):

The importance of genes in organizing the normal brain is underscored by the many ways in which nonstandard genes can give rise to nonstandard minds. When I was an undergraduate an exam question in Abnormal Psychology asked, “What is the best predictor that a person will become schizophrenic?” The answer was, “Having an identical twin who is schizophrenic.” At the time it was a trick question, because the reigning theories of schizophrenia pointed to societal stress, “schizophrenogenic mothers,” double binds, and other life experiences (none of which turned out to have much, if any, importance); hardly anyone thought about genes as a possible cause. But even then the evidence was there: schizophrenia is highly concordant within pairs of identical twins, who share all their DNA and most of their environment, but far less concordant within pairs of fraternal twins, who share only half their DNA (of the DNA that varies in the population) and most of their environment. The trick question could be asked—and would have the same answer—for virtually every cognitive and emotional disorder or difference ever observed. Autism, dyslexia, language delay, language impairment, learning disability, left-handedness, major depressions, bipolar illness, obsessive-compulsive disorder, sexual orientation, and many other conditions run in families, are more concordant in identical than in fraternal twins, are better predicted by people’s biological relatives than by their adoptive relatives, and are poorly predicted by any measurable feature of the environment.

Such experiments have been criticised and the criticisms haven’t been answered. Perhaps if Pinker spent more time looking for flaws in his ideas he wouldn’t be advocating falsehoods.

As for the page Pinker links, it is notable that the page, like Pinker, never bothers to provide any quotes from or even references to the material they claim to criticise. This is unscholarly and anti-rational behaviour. Popper criticised probaiblistic induction and subjective probability, both of which are part of Bayesian epistemology, see for example, Part II, Chapters I and II of Realism and the Aim of Science. Further criticisms can be found in The Beginning of Infinity by David Deutsch, especially Chapter 13.

About conjecturesandrefutations
My name is Alan Forrester. I am interested in science and philosophy: especially David Deutsch, Ayn Rand, Karl Popper and William Godwin.

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