This article describes Leonard K. Nash's theory of science and elements of the context in which he developed it. Nash's involvement with Thomas Kuhn in J. B. Conant's General Education and History of Science program at Harvard is noted, and contrasts between Nash and Kuhn's views of science are indicated. Students of the history of, and theories contributed to, metascience in the 1950s and 1960s (years in which major works of Popper, Polanyi, Hanson, Nagel, Kuhn, Feyerabend and Lakatos saw the light) will find Nash a stimulating thinker, his evolutionist, anti-revolutionary, stance being of particular interest.