One easy way into Karl Barth’s Church Dogmatics is to trace his references to the philosophy of Descartes. He ascribes the liberal-modernism in Protestant theology, to which he was so deeply opposed, to the grip of Cartesian epistemology on theological methodology since the Enlightenment. Paradoxically, he insists on a radicalization of Cartesian considerations about doubt and certainty when he comes to work out the doctrine of creation.

Very early in the first volume of Church Dogmatics (henceforth CD), Barth assails ‘Modernistic dogmatics’, ‘theology since the days of the Enlightenment’ (CD 1/1, page 36, first published in 1932, English translation 1936, revised 1975). He means, of course, Protestant theology: a theology, or a family of theologies one might say, in which ‘church and faith are to be understood as links in a greater nexus of being’, so that dogmatic theology becomes ‘a link in a greater nexus of scientific problems, from the general structural laws of which its own specific conditions of knowledge are to be deduced and its own specific scientific character known’. The mistake with this, according to Barth, is that theology is regarded as having the same epistemological status, requirements, methods and so forth, as any other scientific or scholarly discipline. More specifically, this ‘nexus of problems’ is ‘that of an ontology’, a conception of reality, a metaphysics of being, which— ‘since Descartes‘—is the ontology ‘of a comprehensively explicated self-understanding of human existence which may also at a specific point become the pre-understanding of an existence in the Church or in faith, and therefore the pre-understanding and criterion of theological knowledge’.