Prior to Karl Popper (1902-1994), the philosophers of science had generally sought to explain how scientific theories could be proven to be true. Popper, building upon the doubts expressed in the eighteenth century by David Hume, rejected the possibility of proof in the empirical sciences. While a scientific law could be formulated and tested through laboratory experiment and observations of the real world, no set of observations could exhaustively establish that the law held for all time and all space. It is impossible, for example, directly to observe occasions in the past when the law should have been in operation, or occasions in the future. Popper therefore argued that science proceeds, not by proving its hypotheses or explanations to be true, but by proving them to be false. The task of science is to formulate an explanation of phenomena (and typically phenomena that do not behave according to our preexisting expectations of that behaviour). A good explanation will be such that it will entail certain predictions about future events, and that these events are observable. (Galileo hypothesised that the mass of an object will not influence the velocity with which it falls to the ground.) The explanation is then tested by observing whether the predicted events take place or not. (Galileo allegedly dropped two cannon balls of different mass simultaneously from the top of the Tower at Pisa. They landed together.) If the predicted events do occur,t hen the theory is corroborated (which is to say, that it can be accepted, for the moment, as if it were true). If they do not occur, then the theory is refuted. It has been proven to be false, and must be replaced by a better theory. Theories are continually under test, and as more or perhaps more subtle observations become possible, even a well corroborated theory may eventually prove to be false. Popper uses this argument to distinguish between science and pseudo-science. Pseudoscience is such that it refuses to generate empirically testable predictions, or refuses to accept refutation of a theory when it occurs. For Popper both psychoanalysis and Marxism are pseudo-sciences.
Science therefore thrives only when there is a continual testing of accepted theories. This model of science, and specifically of an open and mutually critical community of scientists, becomes the basis for Popper’s political philosophy. His concept of the ‘open society’ entails that social decisions are not to be made by autocratic planners (and especially not those who, like certain crude Marxists, believe that they are working according to the iron laws of history), but rather through open and rational debate. Any member of the society must be free to criticise any policy proposal, and there must be a real possibility of new ideas being put into practice (and thus subject to empirical testing). For Popper such democratic openness is a precondition for economic growth. Open societies are economically more efficient than closed ones.
Popper’s later work embraced a broad range of philosophical problems, and not least the relationship between his model of scientific inquiry and Darwinian accounts of evolution (in so far as both articulated an account of progress as problem-solving, with potential solutions being rigorously tested in terms of their practicality in the real world). Popper also offered an account of human culture, as what he termed ‘World 3’. World 1 consists of objective and material reality (and thus physical things, animate and inanimate, in the environment). World 2 is composed of subjective, mental phenomena (thoughts, emotions, feelings). World 3 is both objective and mental. It is composed of the cultural products of human minds that gain an autonomy from any individual mind. Language, law, religion, art, science, ethics, the institutions of government and education are all examples of entities within World 3. One implication of this account is that while World 3 is a creation of the human mind, it is capable of having consequences and properties that are unintended by the creator. Popper gives the example of mathematics. The sequence of natural numbers is a human construction, yet, once this sequence exists, facts about it can be discovered, such as the difference between odd and even numbers or the properties of prime numbers. That these properties require discovery demonstrates the objectivity (in the sense of its autonomy from its creator) of World 3.
Source: Cultural Theory The Key Thinkers by Andrew Edgar and Peter Sedgwick, Routledge