Both Pierre Duhem and his successors emphasized that medieval scholastics created a science of mechanics by bringing both observation and mathematical techniques to bear on natural effects. Recent research into medieval and early modern science has suggested that Aristotle's subalternate sciences also were used in this program, although the degree to which the theory of subalternation had been modified is still not entirely clear. This paper focuses on the English tradition of subalternation between 1310 and 1350, and concludes with a discussion of the theory advanced by Thomas Claxton early in the fifteenth century.