Perception as a Capacity for Knowledge is the 2011 Aquinas Lecture delivered by John McDowell on February 27, 2011 at Marquette University. Professor McDowells Lecture is the 75th in this esteemed series hosted by the Philosophy Department at Marquette. Past lecturers include Mortimer Adler, Anton. C. Pegis, Yves Simon, Jacques Maritain, Etienne Gilson, Bernard Lonergan, S.J., John N. Findlay, Alvin Plantinga, Paul Ricoeur, Alasdair MacIntyre, Louis Dupre, Myles Burnyeat, and Margaret Urban Walker. A central theme in much of Professor McDowells work is the harmful effects, in modern philosophy and in the modern reception of premodern philosophy, of a conception of nature that reflects an understanding, in itself perfectly correct, of the proper goals of the natural sciences. In a number of contexts, he has argued that we can free ourselves from the characteristic sorts of philosophical anxiety by recalling the possibility of a less restrictive conception of what it takes for something to be natural.