Aristotle's On Interpretation Ch. 9. segment 19a23-19b4: At the crossroad between actuality and possibility. Where assertions about the future diverge

(19a23-19b4) of Ch. 9: At the crossroad between actuality and possibility. Where assertions about the future diverge

An assertion (ἀπόφανσις) is a meaningful sequence of sounds. When we we voice an assertion, we convey a meaning (νόημα) to our listeners. We understand the meaning of each assertion as a concept which is (i) communicable to others and (ii) corresponds to a thing as it presents itself in the world (πρᾶγμα).

Now, as Aristotle instructs us in Ch. 9 18a28-18a33, one way we differentiate between assertions is based on whether their meaning corresponds to a set of circumstances which occurs in (i) the present, (ii) the past, or (iii) the future. He explains that we situate our assertion in the present when we formulate it with a verb, in the past or future when we formulate it with a verb inflection.

(i) When we make an assertion about the present, we intend for the meaning of what we assert to correspond to an actuality. That is, to a set of circumstances which occurs as we speak. For this reason, our assertion may only either be true or false, depending on whether it accurately reflects what is taking place.

For instance, when we assert that “Socrates runs” it may only either be the case that Socrates is indeed currently running or that he is not. Whatever the case may be, i.e. whether Socrates is running or not, it is necessarily so and cannot be any other way. What we mean with this is that when he is currently running it cannot be the case that he is also not running at the same time. As such, our assertion “Socrates runs”  and its contradictory “Socrates does not run” cannot be true or false at the same time. When the one happens to be true, then its contradictory proves false by necessity. 

(ii) When we make an assertion about a past occurrence, what we communicate corresponds to a set of circumstances which took place at a point in time previous to the current one. Such past circumstances were once an actuality, yet now persist in the present in the mere form of records and recollections. Analogous to assertions about the present, an assertion about the past is only true or false. This depends on whether it correctly conveys what once took place.

To offer an illustration, Socrates could not have both visited and not visited the Oracle of Delphi during his lifetime. He either did visit it or he did not. If he happened to visit Delphi at some point in his life, then it was necessarily the case that he did so when he did so. This is because when Socrates visited the Oracle, he precluded the possibility of him never visiting it. Correspondingly, if Socrates did not happen to visit Delphi, then it was necessarily the case that he never did so. Afterall, had Socrates visited the Oracle even once, the possibility of him never visiting would have been ruled out. As such, only one of the assertions “Socrates never visited the Oracle of Delphi” and “Socrates visited the Oracle of Delphi at least once” can be true or false. If the former is true, then the latter necessarily proves false and vice versa.

By and large, when a set of circumstances takes place, it does so by necessity. What we mean with this is that during that time, no alternative may take place in its stead. This is the case with what took place in the past and what presently takes place. They cannot be otherwise. 

(iii) The future is not set in stone. Where the present may allow for a set of circumstances to come about in the future, this does not mean it needs to do so. It remains a possibility among several. A possibility does not necessitate its inevitability. Rather, it accepts its contradictory as equally a possibility. Put differently, it is neither necessary for a possibility to take place nor is it necessary for it not to take place. What remains necessary, however, is that it either takes place or it does not. In this way, an assertion about a future occurrence only signifies a stance towards the sum of future possibilities. With an affirmation, we set one possibility apart from the rest and claim it will occur. With a negation, we deny a possibility and claim any other will occur instead. 

Let us frame this with an example. When we assert that “Socrates will be at the agora tomorrow morning”, what we communicate neither corresponds to an actuality, i.e. a set of circumstances presently taking place, nor to the record of one that did so in the past. Instead, it corresponds to the sum of possible sets of circumstances which the present permits. These may be countless like the colours of the rainbow. Yet, from the perspective of our assertion, we may express them as two equivalent yet contradictory possibilities: (i) that Socrates will be at the agora and (ii) that he will not be at the agora tomorrow morning. In the first case, one set of circumstances takes precedence over the rest. In the second case, it is superseded by all the rest.

Now, if it is both possible for Socrates to be at the agora tomorrow morning and for him not to be there, then the assertion “Socrates will be at the agora tomorrow morning” cannot be true and it cannot be false. The same holds for its contradictory “Socrates will not be at the agora tomorrow morning”. Instead, they both have an equal chance to prove true or false tomorrow morning. In the meantime, we acknowledge that in a pair of contradictory assertions, it is not necessary for one to be true and the other false. To be precise, when there is both a possibility that a set of circumstances will take place and that it will not, it is neither necessary for an assertion to prove true nor to prove false and the same applies for its contradictory.

Here we bring our discussion of On Int. Ch. 9 to an end.

Key points: (i) The meaning of an assertion about the present corresponds to an actuality, i.e. a set of circumstances which takes place as we speak. (ii) The meaning of an assertion about the past corresponds to the record of what took place before the present. (iii) Both what occurs now and what once occurred are necessary. That is, they cannot be otherwise. Assertions about such occurrences are either true or false (iv) The future, however, is not set in stone. Hence, when we make an assertion about the future, we only communicate our stance towards the sum of possibilities the present permits. (v) The meaning of an assertion about a set of circumstances which has yet to take place corresponds equivalently to the possibility that it does take place and that it does not. (vi) Such assertions are not true or false at the time they are made. Rather, they maintain both the possibility to prove true and to prove false in the future. (vii) For this reason, when two such assertions contradict, it is not necessarily the case that one of them is true and the other false.

“Springtime in the Levant” by Frederic Edwin Church ca. 1879