Karl Popper Falsification Theory (Melvyn Bragg on Radio 4)

8 Feb 07 BBC Radio 4 - from "In Our Time" (click to listen)

Karl Popper is one of the most significant philosophers of the 20th Century, whose ideas about science and politics robustly challenged the accepted ideas of the day. He strongly resisted the prevailing empiricist consensus that scientists' theories could be proved true. He believed that even when a scientific principle had been successfully and repeatedly tested, it was not necessarily true. Instead it had simply not proved false, yet! This became known as the theory of falsification. He called for a clear demarcation between good science, in which theories are constantly challenged, and what he called "pseudo sciences" which couldn't be tested. His debunking of such ideologies led some to describe him as the "murderer of Freud and Marx". So how did Karl Popper change our approach to the philosophy of science? How have scientists and philosophers made use of his ideas? And how are his theories viewed today? Are we any closer to proving scientific principles are "true"

Contributors

John Worrall (JW), Professor of Philosophy of Science at the London School of Economics

Anthony O'Hear (AH), Weston Professor of Philosophy at Buckingham University

Nancy Cartwright (NC), Professor of Philosophy at the LSE and the University of California

KP was born 1902 in Vienna where he obtained a PhD at the University of Vienna. Marxist and Freud & other psychoanalysts (Adler, Jung) treated their theories different from (what Popper called) true scientists like Einstein. In 1919 light passing the sun in a total eclipse of the sun was observed. IF this observation had failed then Einstein would have given up his General Theory of Relativity because the theory would have been falsified.

Marx theory was falsified many times but Marx never gave it up, so Marx was not a true scientist according to Popper.

Psychoanalalysts theories were simply unfalsifiable - Popper called unfalsifiable theories - pseudoscience.

Newton mechanics theories had been confirmed for over 200 years but when it came to the 1919 observations of Einstein theories - some of Newton theories were falsified. This was how science should proceed - it is the criterion of demarcation between science and pseudoscience.

Popper published the Logic of Scientific Discovery in 1930s. Vienna Circle said that you could prove scientific theories by observation & experiment. Popper said you can NEVER PROVE a scientific theory (lots of observations cannot be made and the future might be differant from the past). Scientific theories put themselves up for testing and IF they could be falsified by observation and experiment then these were true scientific theories and not pseudoscience. Uranus was found not to follow Newtonian laws. So Neptune was postulated and then found when telescopes were pointed at where Neptune should have been.

Popper said Science should be a bold imaginative activity - not ONLY systematic fact collecting.

Deductive reasoning is the kind of reasoning in which the conclusion is necessitated by, or reached from, previously known facts (the premises). If the premises are true, the conclusion must be true. This is distinguished from abductive and inductive reasoning, where the premises may predict a high probability of the conclusion, but do not ensure that the conclusion is true.

Deductive reasoning is dependent on its premises. That is, a false premise can possibly lead to a false result, and inconclusive premises will also yield an inconclusive conclusion.

Theory of falsification came from Deductive logic - if premise is true then conclusion must be true. Example: If John lives in London then John lives in South of England (premise). Then we conclude that John MUST live in England. But the problem of Deductive logic is that the conclusions are contained within the premise!

Induction or inductive reasoning, sometimes called inductive logic, is the process of reasoning in which the premises of an argument are believed to support the conclusion but do not ensure it. It is used to ascribe properties or relations to types based on tokens (i.e., on one or a small number of observations or experiences); or to formulate laws based on limited observations of recurring phenomenal patterns. Induction is used, for example, in using specific propositions such as:

This ice is cold.

A billiard ball moves when struck with a cue.

...to infer general propositions such as:

All ice is cold.

All billiard balls struck with a cue move.

Popper said their was no solution to David Hume's Induction logic. Just because their was a pattern of data eg sun rises - we cannot assume (circular thinking) that sun will rise just because it has in the past. Popper said that the Solution was NOT to use induction in science - don't accumulate data then generalise - but do speculate then test. But in practice, scientists DO use inductive generalisations to proceed with science.

Given two alternative theories - use the theory that has not been falsified (YET). Example: Theory of Aerodynamics has survived all the tests. Another theory of flying could be used - but assume that theory has broken down in the past. Anyone in their right mind would sse theory that has not been falsified yet ie. in this case, the Theory of Aerodynamics.