It is commonly held that Karl Barth emphatically rejected the usefulness of philosophy for theology. In this essay I explore the implications of Barth's theological epistemology for the relationship and proper boundaries between philosophy and theology, given its origin in Barth's theology of revelation. I seek to clarify Barth's position with respect to philosophy by distinguishing the contingency of its offence from any necessary incompatibility. Barth does not reject philosophy per se, but the way in which philosophy is typically conducted. This is made explicit through an analysis of Barth's censure of the uncritical acceptance in theology of modernist philosophical presuppositions. I nuance Barth's response to a collection of philosophical assumptions that are rarely distinguished in theological literature. Finally, I highlight a representative instance of Barth's reflections on philosophy in relationship to theology, to demonstrate that the criterion for evaluating the usefulness of philosophical assumptions and methods in the service of theology is the same criterion by which theology is itself evaluated.