Karl Popper's 'Conjectures and Refutations' is a gem of a book based on the thesis that 'we can learn from our mistakes'. Doing so results in theories of knowledge, reason and experience. Knowledge, particularly 'scientific knowledge, progresses by 'unjustified (and unjustifiable) anticipations, by guesses, by tentative solutions to our solutions to our problems, by conjectures'. What controls these conjectures is, 'attempted refutations'. In common with Xenophanes he believes that 'truth' is 'but a woven web of guesses'. There are many sources of knowledge but none has authority and philosophers have not distinguished clearly enough between 'questions of origin and questions of validity'. Thus the proper epidemiological question is not about sources but about assertions. Error can only be detected by criticising the theories or guesses of others and by criticising our own theories or guesses. He writes, 'in our infinite ignorance we are all equal', a lesson some vociferous scientists have yet to learn.
In his late teens Popper decided Marxism, psychoanalysis and individual psychology were 'three theories, though posing as sciences, had in fact more in common with primitive myths than with science; that they resembled astrology rather than astronomy'. Yet for their adherents these myths appeared to have an explanatory power which Popper attributed to their desire to look for confirmations. Such 'confirming evidence should not count except when it is the result of a genuine test of the theory'. In sum, 'the criterion of the scientific status of a theory is its falsifiability or refutability or testability'. Marxists sought to avoid the latter by re-interpreting theory when practice had falsified it. In similar fashion Popper dismissed Freud's psychoanalysis and Adler's individual psychology stating 'these theories describe some facts but in the manner of myths' which are not testable. He argues that most scientific theories originate from myths although the myths may anticipate scientific theories. He also argues that observations are 'interpretations in the light of theories...and for this reason alone they are apt to seem to support those theories in the light of which they were interpreted'. Ultimately, no-one can establish truth by decree, truth itself is above human authority.
Popper challenged the Logical Positivists who argued that scientific statements were those which could be verified by observation, hence metaphysics was not scientific and should be ignored. He proposed a criterion of demarcation in order to distinguish between statements of the empirical sciences and all other statements whether they were of a religious, metaphysical or pseudo-scientific nature. His argument was that for a statement to be ranked as scientific it must be capable of conflicting with possible or conceivable observations. In other words it must be capable of being proved false. This was a response to Wittgenstein's claim that meaningful propositions were truth-functions of elementary or atomic facts which could be established by observation from which deductions could be made. Popper rejected this claim on the grounds that 'no scientific theory can ever be deduced from observation statements, or be described as a truth-function of observation statements'. He argued - as some still do - that Darwinism was not a testable scientific theory but a metaphysical research programme. Although he later agreed natural selection was testable, though difficult to test, many evolutionary biologists claim evidence from empirical testing supports natural selection. Not all agree largely because empirical testing is philosophically based and sociologically verified. As Kuhn's paradigm shift demonstrates scientists often resist challenges to the orthodox establishment of which they are part.
Popper believed science was the pursuit of truth and philosophy an exercise in problem solving. He dismissed much philosophical writing (especially in the Hegelian school) as 'meaningless verbiage'. Discussing Hegelian dialectic as characterised by the triad: thesis, antithesis and synthesis, with the synthesis becoming the thesis of the next triad, he identifies the dialectic as a method of trial and error. He concludes that, 'the dialectic interpretation...will hardly ever help to develop thought' in part because of the loose way in which dialecticians speak about the contradictions explicit in the dialectic process. 'It is not scientific reasoning itself which is based on dialectic; it is only the history and development of scientific theories which can with some success be described in terms of the dialectic method. Hegel's dialectical philosophy was a form of idealism which his successors easily translated into materialism. This is what Marx did, claiming the history of ideas cannot be considered without mentioning 'the conditions of their origin and the situation of their originators'. In Popper's view it was possible for ideas to outweigh economic forces which ultimately led to the collapse of the Soviet Union and its satellite states.
Popper's critique of the dialectic led naturally to an attack on Marxism, in particular on the idea of historicism. Historicism was based on the idea that it was possible for predictions to be made in social matters as effectively as in science. The job of the social sciences was to make historical predictions such as social revolutions. The key to the future lay in understanding the nature of the situation in which mankind found itself. Popper stated that the historicist does not 'derive his historical prophecies from conditional scientific predictions'. Historicism is an example of the conspiracy theory of history derived from the secularisation of religious superstitions. The result is a deification of history which is destroyed by political practice. It lay at the heart of totalitarian and authoritarian rule, standing in stark opposition to his social liberalism. He believed poverty, unemployment, sickness and pain, slavery, religious and racial discrimination, a lack of educational opportunities, rigid class differences and war could be remedied or relieved by social co-operation. Whether any of those things has occurred in the last sixty years is moot. His admission that Kant's 'Critique of Pure Reason' was difficult to understand displays a degree of humility which stands in sharp contrast to those for whom science is truth and dismiss those who do not share their views. Five stars.
This book "Conjectures and Refutations", dedicated to his friend Hayek, contains conferences and texts of the 1950's and the 1960's, so it is the time of maturity for Karl Popper, after his basic work of 1935: "The Logic of Scientific Discovery". Considering the whole book, it is first of all a treatise on philosophy of science, but we find here the general philosophy of Popper, facing the main problems in the theory of knowledge: science, metaphysics, history of philosophy, language, the body-mind question, humanism and reason, and politics. He did apply his theory of knowledge from the Presocratics to the Vienna Circle and the modern "linguistic turn" in the XXth century, studying Hume, Kant, Berkeley, Hegel, Copernic, Newton, Einstein... It is always the same method that appears, of trying and error, or conjectures and refutations (the title), through testing theories, that leads to elimination or corroboration. Corroboration means approaching "truth" according to the theory of Tarski, Popper's reference here. We never reach an absolute certainty, but only temporary results, until the next problems appear, and calling new tests for the scientists and so on... Then, the problematic of the author do help us to give answers to a lot of questions in physics, astronomy, empirical sciences, social sciences, politics and in general philosophy. Upon his logical foundations and his critical rationalism, with his criterion of demarcation: refutation, Popper defended a real and objective knowledge, a free research in science and democracy in politics. (See also "Objective Knowledge" for his evolutionary theory of knowledge).