 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 participating in an obligational disputation. Now, if one considers the possibility that you are running, this possibility must according to Burley be referred to some other time, because of the necessity of the present. You cannot be running now since you are standing now, but afterwards you can of course run. (Kretzmann and Stump 1988, 394.)