This seminal tome laid the foundations for the rest of Popper's work. It offered an analysis of the procedure to be used in scientific work and a criterion for the meaning of the statements produced in such work. According to Popper, the researcher should begin by proposing hypotheses. The collection of data is guided by a theoretical preconception concerning what is relevant or important. The examination of causal connections between phenomena is also guided by leading hypotheses. Such a hypothesis is scientific only if one can derive from it particular observation statements that, if falsified by the facts, would refute the hypothesis. A statement is meaningful, therefore, if and only if there is a way it can be falsified. Hence the researcher should strive to refute rather than to confirm his hypotheses. Refutation is real advancement because it clears the field of a likely hypothesis.
`One cannot help feeling that, if it had been translated as soon as it had been originally published, philosophy in this country might have been saved some detours. Professor Popper's thesis has that quality of greatness that, once seen, it appears simple and almost obvious' - Times Literary Supplement