Scholars disagree about whether or not there was a break between Hobbes's earlier, humanistic period and his later, scientific period. This article contends that, when judged on the epistemological level, Hobbes broke with his humanist past by exchanging the probability of the humanists' rhetorical epistemology for the certainty of scientific knowledge. Hobbes believed that only certainty could shield against the anarchy of civil war. Hobbes's rejection of the humanists' epistemology had practical consequences for the issue of religious toleration. The humanists, like the ancient rhetoricians, turned to consensus as the criterion of truth. By relying on consensus, the humanists were able to reduce the area of intolerance; only those beliefs on which there existed a broad-based agreement of the Christian faithful were viewed as essential. Hobbes's rejection of the humanists' epistemology, which included their concept of consensus, also entailed his rejection of their particular defense of toleration. Nevertheless, since Hobbesian political theory is, in principle, neutral on the question of toleration, there is nothing in the logic of Hobbes's argument that would preclude a greater degree of toleration, based on the sovereign's prudential assessment of existing circumstances.