Writing about the Popperian “turns”provides an opportunity to acknowledge the work of Popper’s research assistants and editors who helped along the way. Think of them as the Sorcerer’s apprentices, or perhaps the elves in Santa’s toy factory. Joe Agassi’s book about his time in Popper’s workshop contains a photo of all the research assistants: himself, Ian Jarvie, Alan Musgrave, David Miller, Arne Petersen and Jeremy Shearmur. Feyerabend was supposed to be the first but he did not report for duty.
It would be nice to have a photo of Popper’s longest serving and most dedicated helper of all, the gracious Lady Popper, known as “Hennie” after her family name. Two other important helpers were his editors, Bill Bartley who finally got the manuscript of The Postscript out the door to the printer and Mark Notturno who edited Popper’s last collections of papers and worked on his series of introductory lectures at the LSE.
I mention the helpers in connection with the “turns”; conjectural (or non-justificationist), objective, social and metaphysical because for good reasons or bad I tend to associate some of the helpers with some of the turns.
I have written about Bartley and his work on the conjectural or non-justificationist turn and put some of his work on line. Of course all Popper’s helpers participated in the conjectural turn and Bartley was the one who made the most out of non-justificationism. Miller was strong in this respect as well, although Popper and others were not entirely satisfied with the way both Bartley and Miller developed critical rationalism.
Ian Jarvie was good on objective knowledge and his Concepts and Society was a book that I would have liked to write:) He really nailed the social turn as well, see his beautiful book The Republic of Science: The Emergence of Popper’s Social View of Science.
Joe Agassi does beautiful things too but he has written too many books and his articles are too long for busy to people to read. I think of him as the metaphysical ghost in the Popperian machine, or at least the person who did so much to keep metaphysics in the frame and not down the drain where the positivists wanted to send it.
Jeremy Shearmur was very helpful for me, starting with hospitality and introductions to local philosophers when I was in England in 1972. He also sent bundles of books including some by Talcott Parsons which enabled me to pick up the common ground of the early Parsons (up to 1937) with von Mises and Popper. And his book on the political thought of Karl Popper indicated the way that Popper’s ideas support classical liberalism despite the fact that they are usually interpreted to support the interventions of social democracy.
Radnitzky was not close to Popper (as far as I know) but he was a big helper with Bartley to promote the evolutionary approach (which is not among the list of four “turns” for some reason, I suppose I don’t want to describe everything that Popper did as a “turn”).