Biard's chapter tackles the issue of intentionality from Buridan's perspective, namely, dealing with the apparent logical paradoxes emerging in intentional contexts, such as the break-down of the substitutivity of identity, or reference to and quantification over non-existents in the context of terms signifying mental acts. Paradoxes arising from the use of intentional terms in propositions had been discussed by philosophers since the twelfth century, but Buridan's explanation of the semantics of propositions containing verbs of knowing, believing, wishing, etc., whether joined with simple terms or with propositions, is much more sophisticated than that found in any other medieval (or, for that matter, modern) work. Buridan explores aspects of intentionality ranging far beyond the use of verbs expressing propositional attitudes. His original theory of appellatio rationis provides not only a plausible account of how the logical paradoxes emerging in intentional contexts ought to be treated in a consistent manner, but also the "down-to-earth" philosophical rationale as to why such paradoxes emerge in these contexts in the first place, namely, the fact that mental acts signified by psychological terms generating intentional contexts always concern their objects by means of the concepts (rationes) of these objects.