Ockham’s own formulations of his Razor state that one should only include a given entity in one’s ontology when one has either sensory evidence, demonstrative argument, or theological authority in favor of it. But how does Ockham decide which theological claims to treat as data for theory construction? Here I show how over time (perhaps in no small part due to pressure and attention from ecclesiastical censors) Ockham refined and changed the way he formulated his Razor, particularly the “authority clause” (...) that states that authoritative theological pronouncements constitute a reason for postulating entities in one’s ontology. This refinement proceeded across three stages, culminating in the political writings of the final period of his life, in which Ockham offers reasons (not previously mentioned in scholarly discussions of Ockham’s Razor) against granting ecclesial authority any significant role to play in settling ontological questions. (shrink)