Post-Cartesian theories of psychology or epistemology can be generally located in one of two competing paradigms-the work of the later Wittgenstein, Kuhn and others being exemplars of the first and the work of Popper, Campbell, Lorenz and others being exemplars of the second (Munz, 1985, 1987). The proponents of the first, "closed-circle theorists", who have worn incommensurability and relativism almost as a badge of enlightenment, look to sociology or social psychology as the basis for meaning and intentionality, while evolutionary or natural selection epistemologists, proponents of the second, look to biology, or, more particularly, to Darwinian evolutionary theory as the ground for the epistemic dimension.

Closed-Circle Theory and The Sociology of Knowledge

Closed-circle theory finds roots in the functionalism of Durkheim and Malinowski, and the "sociology of knowledge" of Mannheim. Earlier roots go back to Marx and Engels' work on ideology, and Spencer before. While the common thread to all these various ancestors was the idea that social ordering determines individual action, it should not be construed that all were closed-circle theorists in the extremized post-modern form of Wittgenstein and Kuhn.
Social systems, according to Durkheim (1895/1938), were said to have a reality outside the existence of individual humans that acts to determine their meaningful relations and intentional behavior. In explicit reaction to "psychologism", the idea that cultural systems are rational constructions of individual intentional agents, as well as the prevalent evolutionary views of history or culture, Malinowski held that human social or cultural systems were effectively closed circles where the parts all function to maintain the whole. Given that the circular relations of such a system were seen to refer back to themselves-that the function of the system is to maintain itself-they were said to exist sui generis. Everything is explained with respect to something else that happens internal to the circular relations of the system.
Wittgenstein further extremized this view by transposing it into a sociological version of the Cartesian circle. Rather than the circular relations constituting the self-referentiality of the human mind, Wittgenstein's circle was constituted through the intersubjective circular relations of humans within a cultural system. Meanings, said Wittgenstein, are formulated and stated in "language games" consisting of a set of rules that constitute closed circles of meanings. Because there is no individual language there can be no individual meanings, and because such systems are closed circles there can be no ostensive pointing or reference to anything outside the system (i.e., an objective "world"). What is more, because meaning is entirely relative to the rules of each system and thus meaning invariance is denied, such circles of meaning are incommensurable with respect to each other. Truth thus varies from one closed circle to the next, and can only be measured with respect to the rules or authority of a particular community.
In Kuhn's influential history and philosophy of science Wittgenstein's closed-circle language games were turned into paradigms, and the history of science the shift from one paradigm to another (scientific revolutions). Since reality is taken to be an ideal construction of human cognizers operating under particular paradigms, and since paradigms as closed circles are incommensurable with each other there is no progress in science on Kuhn's view-without meaning invariance there is no way to make a comparison. On this view, Einstein's physics does not subsume or explain Newton's but rejects it. The post-modern structuralism of Foucault, Derrida, and the post-modern pragmatism of Rorty, which uses Foucault, in effect, to justify Wittgenstein (Munz, 1987), are all closed circle theories that share the common premises of the relativity of meaning to circularly closed systems, and the incommensurability of such systems with respect to each other and an external world. Closed-circle theory carries forward the anti-realist position of positivism, but attacks its rationality.