“The question remains to know whether a thing can be called possible, or again in-potentiality, when it will never be the case. In other words, can the possible designate the unreal, that is to say that which, while not being contradictory, is not and will never be the case? It is to this question that Theta 5 responds: the text opens with a new division of dunamis, according to which it is innate (for example, sensation) or acquired (by practice, like the art of playing the flute, or by study. It also recalls the distinction between rational and irrational powers” (Aubry, Dieu san la puissance, 2nd ed., ch. 4, p. 126, my translation).

Aubry notes that Aristotle introduces a new definition of the possible (dynaton). “The possible is in effect relative to actual circumstances: that which is possible is so kai pote kai pos, at a given moment and in a certain way…. Aristotle has a tendency to think the possible not as that which can be conceived, and is non-contradictory, but as that which can be: in other words, he does not distinguish neatly between logical possibility and real possibility, and in effect resists calling possible that which, while being capable of being in the sense that it is non-contradictory, will never be. In virtue of this new definition, one indeed calls possible that which, if all the conditions are present, must be actualized, and indeed must necessarily be actualized. The formula is one of determinism” (p. 127).

She immediately goes on to explain how Aristotle limits this determinism to irrational or natural powers, as opposed to rational ones. I would supplement this with another distinction.

In the bigger picture, even in the natural realm I think that for Aristotle, there is no strict predetermination of the overall unfolding of events. An animal gets its food in one way and not another on a given day, but this is in part due to “accident” in the ways that things come together.

The case Aubry is speaking about here is a hypothetical consideration of what would be really possible, at a given moment, and given a complete definition of the applicable circumstances. In this case, which by hypothesis is fully specified, Aristotle wants to say there should be a determinate answer, which should be subject to hypothetical necessity.

But in the case in which we consider what is really possible, this is not hypothetical, because we are not working from a hypothesis at all. Neither is there any “if”, nor are we “given” anything specific. We do not have a complete specification of the applicable circumstances. So here the conditions for hypothetical necessity do not apply. If we cannot even say what the hypothesis is, we cannot claim to draw a necessary conclusion. Accordingly, what is really possible cannot be answered in terms of hypothetical necessity.

Hypothetical necessity is a viable kind of claim because it is specific and delimited in its scope of applicability. It is also all that is needed to explain the successes of science and engineering. Given certain definite things, we can say with confidence that something definite will happen. We can iteratively improve our hypotheses and level of confidence as we go.

What is necessary for Aristotle is just what always follows. The applicability of “always” in a generalization about the natural world (as distinct from, say, mathematics or formal logic) is a question of fact. No implacable force stands behind it. And what always follows is implicitly bounded by our knowledge. “Always” simply means we have never encountered an exception. If we did, we would need to look for additional conditions to explain the new case. Necessity belongs in the register of a certain kind of intelligibility of what happens, not in the raw occurrence of events.

What I mean to have been explaining here is that if Aristotle appears to endorse a limited “determinism” with regard to natural powers, the terms in which this is expressed further limit it to a notion grounded in hypothetical necessity. The reason this is so important is that hypothetical necessity is fully compatible with the absence of predetermination, whereas determinism is commonly associated with predetermination. I would prefer to simply say that natural powers can be analyzed in terms of hypothetical necessity. And it turns out that Aubry refutes this appearance two pages later.

Next in this series: Potentiality and Contingency