Peter Machameris professor of history and philosophy of science, University of Pittsburgh. He is coeditor, with Gereon Wolters, ofScience, Values, and Objectivity, Theory and Method in the Neurosciences, and other books. Gereon Woltersis professor of philosophy and deputy director of the Center for Philosophy of Science at the University of Konstanz. He is coeditor ofConcepts, Theories, and Rationality in the Biological SciencesandLogic, Language, and the Structure of Scientific Theories,among other books.