 De Libera has placed this work at Oxford c. 1250, but notes the presence of Parisian teachings in the text. The title given in the Seville MS, Summulae super totam logicam, provides a better sense of the nature of the work. To summarize De Libera, this is the mature work of a practiced teacher, not the work of a beginner. It is ahead of other works of the 1240s in the skillful manner in which it examines Aristotle and other newly translated works in philosophy and science. The work is important for two new semantic positions: (1) the doctrine of univocal appellation and (2) the doctrine of “empty classes” in predication. For Bacon, a word cannot be applied in a univocal manner to both an entity and a non-entity. This position will provide Bacon with a basis for his attack on Richard Rufus of Cornwall in his works after 1260, and especially in the Compendium studii theologiae (1292). This attack was not targeted at Rufus alone; it is written in opposition to the common teaching of the time at Paris, according to which a word has a natural meaning and once that meaning is given, it remains a constant. For example, the term ‘Caesar’ can cover both the once living Caesar and the now dead Caesar. Bacon rejects this on the grounds that for him, terms are imposed on “present things” and there is nothing in common between an entity and a non-entity or between the past, present, and future. Hence, Bacon is opposed to the notion of “habitual being”. Thus, terms have present appellation and their reference to the past and future must be accidental. For Bacon, name and signification are imposed on the present object, and these are opened to past and present on the basis of verbal tense. One might call it “supposition through itself for present things”. Another important aspect of SD is the complex theory of determination found in the composition and division of the propositional sense.