The Open Society and Its Enemies (Princeton Classics)

by Karl Popper

This is what we call testing a theory—to see whether we cannot find a flaw in it. But although the facts are collected with an eye upon the theory, and will confirm it as long as the theory stands up to these tests, they are more than merely a kind of empty repetition of a preconceived theory. They confirm the theory only if they are the results of unsuccessful attempts to overthrow its predictions, and therefore a telling testimony in its favour. So it is, I hold, the possibility of overthrowing it, or its falsifiability, that constitutes the possibility of testing it, and therefore the scientific character of a theory; and the fact that all tests of a theory are attempted falsifications of predictions derived with its help, furnishes the clue to scientific method2. This view of scientific method is corroborated by the history of science, which shows that scientific theories are often overthrown by experiments, and that the overthrow of theories is indeed the vehicle of scientific progress. The contention that science is circular cannot be upheld.