ABSTRACT
According to Robert Fogelin, rational discourse is no longer possible where two irreconcilable certainties meet. This position is criticized here by taking up the distinction between “grounding” and “support” developed by Anselm W. Müller in the vein of Ludwig Wittgenstein. The asymmetrical relation of “grounding” and the symmetrical relation of “support” (or, coherence) each structure the totality of rational beliefs. In doing so, they form independent and complementary patterns of rationality. In cases of “deep disagreement,” it is true that there can be no arguments based on grounds. Nevertheless, it remains possible to challenge the respective certainties by the criterion of support.
