Richard Robin said that Peirce's idea of a normative science grew out of his study of the norms that govern scientific inquiry. This paper develops the suggested dialectic of norms of science and science of norms and examines the role that Peirce claimed observation plays in normative judgment. Peirce's doctrine is compared to recent attacks on the fact/value dichotomy. Putnam's view that there can be objectivity without metaphysics is disputed: observation in the natural sciences presupposes physical causality, while normative judgment presupposes final causality. Except for logic, Peirce did little within normative science; what is important is its possibility, which depends on the relations among the three sciences that Peirce sketched, as this shows how unscientific normative judgment may also be objective.