This paper explores an apparent tension in Descartes\u27 practical philosophy between an agent\u27s commitment to the search for practical knowledge and the necessity for the agent to act, at least sometimes, on the basis of a judgment he recognizes (or suspects) to be uncertain, and so possibly false. The main argument of the paper is that the psychological mechanisms through which the agent brings himself to act with certainty on the basis of uncertain judgments threatens the very happiness that is the good of Descrates\u27 practical philosophy. More specificaly, the worry is that one cannot maintain a real commitment to the search for practical knowledge while at the same time recognizing that one\u27s knowledge is inadequate, and still avoid the kind of anxiety and irresolution that Descartes seems to think are the greatest threats to human happiness
