Peirce's account of how we come to settle our opinions, first printed in Popular Science Monthly in November 1877 as the opening paper of his “Illustrations of the Logic of Science”. Inquiry, he argues, is the struggle to escape the irritation of doubt and reach a settled belief, and he weighs four ways of fixing belief: tenacity, authority, the a priori method, and the method of science, the only one that answers to something outside our own minds. It is one of the founding texts of pragmatism.