 The most prolific category of probable propositions were opinions in the medieval technical sense of this term. An opinion (opinio) was often defined as a proposition held to be true but which the person holding it feared might be wrong (see Byrne 1968, Franklin 2001). This was only one of several medieval understandings of opinion. Robert Grosseteste (∼1175–1253) reminded his readers that opinio could be understood in three  ways.[5]  According to the simplest meaning, opinion stood for any cognition characterized by assent; and, in this understanding, propositions expressing knowledge or conviction were also opinions. According to a more proper definition, opinion denoted assent to a proposition with a fear that the opposite might be true. Finally, according to the most precise definitions, opinions were limited to contingent propositions to which assent was given and the opposite of which were somehow feared to be true. Grosseteste’s distinctions show that thirteenth-century scholastics were already aware that the term opinio was used far from uniformly by contemporary authors. That said, it should nevertheless be kept in mind that medieval discussions of the use of probable opinions predominantly operated on the basis of the second meaning of opinio as a proposition to which assent was given and which was accompanied by a fear that the opposite might be true. The fear in question resulted at least in part from an awareness that one’s judgment might be fallible. According to a widely observed medieval ranking of epistemological confidence and doxological firmness, the category of opinion stood below faith or full conviction (fides) and knowledge  (scientia).[6]  All three epistemic attitudes involved assent, but only faith and knowledge implied full subjective certainty (certitudo).