Abstract Philosophy before and after mid-century is united in a rejection of a central goal of traditional epistemology from Plato to Boole: a theory of discovery. Plato and Aristotle thought the goal of philosophy, among other goals, was to provide methods for coming to have knowledge. This same conception utterly dominated philosophy in the seventeenth century. It was Descartes’ claim to have found such a method, and the disputes between him and his critics were in part over what it is to be a method of discovery at all. Leibniz not only advanced the conception of method, but provided a thesis about it that guided logical investigations into the twentieth century. In my view, the central eighteenth-century dispute in philosophy, between Hume and Kant, was fundamentally about whether we can have methods of inquiry that can be known to be reliable. The latter part of the century provided in Richard Price’s interpretation of Bayes’ probabilism yet another proposal for a universal method of discovery. English-speaking philosophers of the succeeding century were equally absorbed with discovery: John Stuart Mill popularized a method plagarized from Bacon and, in aid of a method for discovering causal relations from probabilities, George Boole made the largest advance in logical theory since Aristotle.