Aristotle was not, as is often charged, an "armchair theorist," spinning scientific theories out of his head (or out of his philosophy), theories which "held back the course of science for two thousand years"; he was a great scientist, whose treatises, especially in biology, provided a model of proper scientific work for centuries. And, though, as his admirers have pointed out, he was in fact a brilliant and careful observer, some of whose findings were not rediscovered util the 19th and early 20th centuries, his greatness as a scientist does not lie in that.

It lies rather, as these lectures aim to show in the systematic and explanatory character of his work in––broadly speaking, the epistemology he practiced. It lies specifically, in: (1) the range of the data he collected and the care with which he collected it; (2) the systematic way he organized that range of data; (3) the way he explained the data he collected and organized; and (4) the way he organized his explanations into a comprehensive body of scientific understanding.

Attention will be given both to Aristotle's practice as a scientist (focusing here on his great biological studies), and to his philosophy of science, with emphasis on the way, according to Aristotle, proper theory derives, step by careful and complicated step, from detailed and careful observation of reality. (Based in part on a lecture given at The Jefferson School in 1987.)