Abstract

In the fourteenth century, Duns Scotus suggested that the proper analysis of modality required not just moments of time but also “moments of nature”. In making this suggestion, he broke with an influential view first presented by Diodorus in the early Hellenistic period, and might even be said to have been the inventor of “possible worlds”. In this essay we take Scotus’ suggestion seriously devising first a double-index logic and then introducing the temporal order. Finally, using the temporal order, we define a modal order. This allows us to present modal logic without the usual interpretive questions arising concerning the relation called variously ‘accessibility’, ‘alternativeness’, and, ‘relative possibility.’ The system in which this analysis is done is one of those which have come to be called a hybrid logic.