Karl Popper

Sir Karl Popper (1902-1994) was an Austrian-born philosopher of science widely regarded as one of the greatest philosophers of science of the 20th century, who influenced the philosophy of science and politics.

Philosophy of Science

Falsifiability

In his seminal work, The Logic of Scientific Discovery, Karl Popper repudiated induction, and proposed the bright line of falsifiability as a demarcation between science and non-science. In order to be scientific, a theory must be testable, and the results of the testing must either corroborate the theory, or falsify it. A proposed theory is falsifiable, if it is conceivable to conduct an experiment that would either substantiate or disprove the theory. For example, Newton's law of gravity was a valid scientific theory because it is falsifiable; that is, the Law of Gravity is experimentally testable, and a measurement taken that violates Newton's law would falsify it, while a measurement that substantiates the theory would corroborate it.

While chemistry, Newtonian physics among others are science, metaphysics, pseudoscience, and Darwinian evolution are not scientific.

Universal Laws

In science Popper proposed a falsifiability criterion for the demarcation of science from pseudoscience as a result of his analysis of universal laws. Universal laws have a logical structure which precludes certain existential statements: universal laws are a negation of an existential proposition. Popper's example was that of the color of swans. The universal statement "all swans are white" implies the negative existential statement "no swans of a color other than white exist". To verify the negative existential we would need to trawl through the universe to ensure that no non-white swan existed anywhere in time or space. Conversely if we saw just one black swan we could confirm the existential statement "black swans exist" and refute the universal "all swans are white".

Popper was uncompromising in his rejection of any attempt to take confirming instances as increasing the legitimacy, likelihood, reasonableness or probability of the universal statement. No matter how many white swans you see you are no more able to assume that all swans are white than if you had seen just the one white swan. The ease with which “confirming” instances can be found lead Popper to the conclusion that an attempted verification of a universal law is worse than useless: to be science universal laws must be capable of being put to the test, to be falsifiable.

Politics

A refugee from Austria after the rise of Nazism, Popper dedicated the war years to the study of the roots of totalitarian thought. The “Open Society and its Enemies” analysed the contribution, as he saw it, of Plato, Hegel and Marx to an anti-rational tribalistic “closed society”. The close society was, for Popper, marked by a lack of criticism of established ideas (established societal norms being treated not as societal norms but as “taboo” or “the natural order”) together with a collectivism that subjected the individual to the group goal.

Popper also saw “historicist” views and underpinning much of the thought behind the “closed” society. “Historicism”, dealt with in “The Poverty of Historicism” and criticised throughout the “Open Society”, both sees historical laws of development and bases much of its morality on these supposed laws.

Sources

• Stanford, Encyclopedia of Philosophy (2006-10-09), Karl Popper, Stanford Encyclopedia of Philosophy Retrived on 2007-05-14