 Ammonius, like Boethius, whose answer is somewhat more complicated, attacks the problem by means of his interpretation of Aristotle’s opening remark in the chapter (18a28 ff.) that, while the rule that, of every contradictory pair of sentences, one is true and one false holds among sentences about what is or has happened, as well as sentences about universals taken universally and for singulars in the present or past tense, for universals not said universally it is not necessary, as he has explained in the preceding; “but in the case of future singulars it is not the same.” Ammonius interprets “it is not the same” as indicating a doctrine that sentences about future singular contingent events ‘divide the true and false’ (i.e., obey the principle of bivalence) but do so in an indefinite, ‘not in a definite manner’ (ouk aphōrismenōs): either there will be a sea-battle tomorrow or there will not be one, and certainly there will not both be one and not, but whichever of these two will turn out to be the case, the sentence correctly predicting that outcome is true (and the other false) only in an indefinite, not a definite way. Thus it is not “possible in a definite manner to say which of them will be true and which will be false, since the thing has not already occurred but can both occur and not occur” (130,23 ff.).