 One of the most important debates at Oxford around 1320–30 concerned the proper object of scientific knowledge. When we know something scientifically, is our knowledge about external things (the earth interposed between the sun and the moon), propositions (‘The moon is eclipsed’), or some other more complex state of affairs? Crathorn is believed to have participated in the development of the idea that the proper object of science is neither the external thing nor the proposition (as Ockham and Holkot had argued), but the ‘total significate’ of that proposition (Tachau 1987). Typically, the total significate would include not only external things but also the premises and other assumptions that generate our assent to the proposition as the conclusion of a piece of demonstrative reasoning.