Three 13th-century views of quantified modal logic

Abstract

There are two reasons why medieval logic is of interest to modern logician: One is to see how similar it is to modern logic and the other is to see how different it is. We study three 13th-century works on modal logic and give two examples of how their views of modal logic differ from modern views of the same: the nature of modality and the truth conditions for modal sentences. Because of the different goals of the medieval logicians, modern logicians must take care in arguing for or against the correctness of the medieval logical theories