Gary Hatfield received the PhD from the University of Wisconsin--Madison in 1979, then taught at Harvard and Johns Hopkins before coming to Penn in 1987. He works in the history of modern philosophy, the philosophy of psychology, theories of vision, and the philosophy of science. In 1990 he published The Natural and the Normative: Theories of Spatial Perception from Kant to Helmholtz; his book on Descartes and the Meditations appeared in 2003; Perception and Cognition: Essays in the Philosophy of Psychology was published by the Clarendon Press in 2009. In 2012, an edited volume (co-edited with the psychologist Sarah Allred) arising from an IRCS workshop on the constancies appeared from Oxford: Visual Experience. The revised edition of his translation of Kant's Prolegomena to Any Future Metaphysics appeared in 2004. He is a member of the Institute for Research in Cognitive Science, the Center for Cognitive Neuroscience, the Penn Perception group, and the History and Sociology of Science Graduate Group. He has directed dissertations in history of philosophy, philosophy of psychology, and philosophy and history of science. He has long been fascinated by visual perception and the mind–body problem.