 Anything more systematic than this has to be drawn out from Abelard’s definition of modal sentences and their semantic interpretation. Thom has done this in his book (Thom 2003), where he claims that there is a very specific system developed that is not at all similar to Aristotle’s modal system. Abelard was therefore not attempting an interpretation of Aristotle, but must be seen as developing a new system based on his reading of de re sentences. But this project must overcome several problems, particularly since Abelard cannot use the conversion rule.