Three 13th-century views of quantified modal logic
Sara Uckelman

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 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.