Truth and Concepts: the Role of the oratio mentalis in William of Ockham and John Buridan

This article aims to elucidate the distinct roles that mental language occupies in the theories of William of Ockham and John Buridan, focusing on their differing approaches to the problem of truth. The Venerabilis Inceptor believes that both mental propositions and spoken or written propositions can be properly true or false. Conversely, Buridan contends that only concepts can be true, whereas spoken and written languages possess truth merely in a metaphorical sense. This divergence underscores a fundamental difference in their nominalist frameworks. Ockham views semantic functions as sufficient to bridge language and reality. For this reason, he sees no need for a strict separation between concepts and other linguistic signs. Buridan, however, argues that semantics must be grounded in something intrinsic to the mind. Concepts, indeed, denote things only insofar as they enable us to know them in a specific way. In this epistemological-semantic duality, mental language assumes functions that spoken and written language cannot replicate.