It is often said that an argument is valid if and only if it is impossible for its premises to be jointly true and its conclusion false. Usually there is little harm in saying this but it places the concept of truth at the very heart of logic and, given how complex and obscure that concept is, one might wonder if trouble arises from this.

It does - in at least two contexts. One of these was explored in the first half of the fourteenth century by Jean Buridan and by the mysterious figure known as the Pseudo-Scotus of the Questions on the Prior Analytics printed in the edition of Scotus's works edited by Luke Wadding. Buridan thought that the bearers of truth were particular sentence-tokens; he thought of ttuth as a property of those tokens and he thought that nothing had properties unless it existed.