Time and modality. When discussing modalities in his Ordinatio (I, d. 38, 2), John Duns Scotus rejects a principle which he calls an obligational rule, namely that with a false positio one must “deny the present instant”. And in fact, Walter Burley (writing roughly at the same time) mentions this as a valid, useful rule. The reasoning behind the rule is the necessity of the present. For example, suppose “you are running” is the false positum when you are in fact standing in a university hall and