the opposite direction by exception.

Now that which is must needs be when it is, and that which is not

must needs not be when it is not. Yet it cannot be said without

qualification that all existence and non-existence is the outcome of

necessity. For there is a difference between saying that that which

is, when it is, must needs be, and simply saying that all that is must

needs be, and similarly in the case of that which is not. In the case,

also, of two contradictory propositions this holds good. Everything

must either be or not be, whether in the present or in the future, but

it is not always possible to distinguish and state determinately which

of these alternatives must necessarily come about.

Let me illustrate. A sea-fight must either take place to-morrow or

not, but it is not necessary that it should take place to-morrow,

neither is it necessary that it should not take place, yet it is

necessary that it either should or should not take place to-morrow.

Since propositions correspond with facts, it is evident that when in

future events there is a real alternative, and a potentiality in

contrary directions, the corresponding affirmation and denial have the

same character.

This is the case with regard to that which is not always existent or

not always nonexistent. One of the two propositions in such

instances must be true and the other false, but we cannot say

determinately that this or that is false, but must leave the

alternative undecided. One may indeed be more likely to be true than

the other, but it cannot be either actually true or actually false. It

is therefore plain that it is not necessary that of an affirmation and

a denial one should be true and the other false. For in the case of

that which exists potentially, but not actually, the rule which

applies to that which exists actually does not hold good. The case

is rather as we have indicated.



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