Popper,
Karl Raimund (1902-1994):
Austrian philosopher of science.
Popper's first major contribution to philosophy was his novel solution to the problem of the demarcation of science. According to the time-honoured view, science, properly so called, is distinguished by its inductive method - by its characteristic use of observation and experiment, as opposed to purely logical analysis, to establish its results. The great difficulty was that no run of favourable observational data, however long and unbroken, is logically sufficient to establish the truth of an unrestricted generalization...
Popper accepted that unrestricted generalizations could not be verified. But, he pointed out, they could be falsified. (While no amount of observation of black crows verifies the statement "All crows are black", one - properly authenticated - observation of a white crow falsifies it.) And falsifiability, for Popper, is the hallmark of science.
A Dictionary Of Philosophy. Second edition. (Pan Books 1984).