From group selection to ecological niches. Popper’s rethinking of evolution in the light of Hayek’s theory of culture

Hayek’s “Rules, Perception and Intelligibility” (1963) discusses the function of a common framework in making other people’s conduct intelligible to us. Popper’s admiration for the article partly derives from the fact that it concludes that such a framework cannot be stated fully and explicitly. In “Notes on the Evolution of Systems of Rules of Conduct” (1967) Hayek concentrates on the evolution of such a framework rather than on its functions. The article proposes a theory of cultural evolution. In this context Hayek introduces group selection. Popper transforms and generalizes this into a theory of ecological niches in all evolutionary processes, a falsifiable theory. This particular influence of Hayek’s on Popper is part of an exchange – mostly in correspondence – about Hayek’s mind-body theory of The Sensory Order (1952). Popper criticized what he called Hayek’s “causal theory” of the mind, which, according to Popper, could not explain the higher functions of language. Hayek took up that challenge – unsuccessfully - in a manuscript that was never published, but that forms the basis of his “Rules” article. The paper describes the debate between Popper and Hayek. It argues that their different approaches to the mind-body problem lie at the basis of other disagreements between the two authors, particularly in their social philosophies. It also argues that all these differences derive from the different directions they take from the philosophy of David Hume: whereas Popper follows the path of scepticism and anti-inductivism, Hayek takes the empiricist and conservative road.