Hayek and Popper: smothered giants of the Twentieth Century

Possibly the most important is the "conjectural turn" to acknowledge that even our most respected and apparently well-supported theories (like Newtonian mechanics) may be found wanting in the light of  new developments. 

The second is to focus on objective, public or inter-subjective knowledge rather than the subjective beliefs which are the standard “stock in trade” of academic epistemology.

The third is the social turn to acknowledge the function of "rules of the game" of science; these are the methodological conventions like replication, repeatability, criteria for  statistical testing, and the protocols for reporting and publication, including peer review.  The social turn draws attention to influential aspects of the institutional context, such as the source of funding,  and it can be found in Popper's work well before Kuhn and the sociology of knowledge appeared.  He did not pursue that line in depth because his interests were elsewhere, but the signal that he gave was clear enough, especially near the end of The Poverty of Historicism and in Chapter 23 of The Open Society and its Enemies.

The fourth is to abandon extended conceptual analysis and the definition of terms, which he called essentialism.  Instead the focus should be on theories and practical policies, on the problems that need to be solved and the comparative merits of the rival contenders that claim to solve them.

The fifth is the evolutionary or biological turn.

The sixth is the revival of  metaphysics in the heart of the philosophy of science with a theory of “metaphysical research programs” which Lakatos borrowed and re-branded as a theory of scientific research programs.

None of those turns are unique to Popper but the combination is very powerful and his career can be described as the application of those turns to a wide range of problems in philosophy, physics  and the social sciences.

The Poverty of Historicism and The Open Society and its Enemies.

Popper wrote these books in New Zealand while the outcome of the war was in doubt and 16 of his relatives perished in the Holocaust.  The Poverty of Historicism was published as a series of articles during 1944/45 and in book form in 1957. The final sections of this work describe  "Situational Analysis" which Popper proposed as a general methodology for the social sciences.

The Open Society and its Enemies, almost 800 pages, including 300 pages of notes in small print, should have been condensed by Readers Digest (like Hayek’s The Road to Serfdom).  It was  a major diversion from Popper’s primary interests which he took on as his contribution to the war effort.

 Conjectures and Refutations

The  1963  collection of papers in Conjectures and Refutations demonstrated the full range of Popper's interests more effectively than The Poverty and The Logic of Scientific Discovery.  However  by this time his stocks were falling under the influence of Kuhn and other critics such as Feyerabend and Lakatos . They energetically promulgated the Standard Errors of interpretation of Popper's ideas and so generations of students were  misled and some of these  student became authors and wrote misleading books.