The couple dynamis/energeia (for lack of better English terms, potentiality and actuality) has excited my imagination for nearly 50 years. There are at least three huge, unprecedented innovations in Aristotle’s concept, which I find still immensely and freshly relevant today.
From the pre-Socratics all the way to the present, the great majority of attempts at ultimate explanation have aimed at a monomorphic account of some sort or other — an account in a single shape, whether in the form of simple assertions about how things are, or of an elaborate system following a single order of development. Against this background, Aristotle’s thinking stands out as richly polymorphic and polyphonous. Things are analyzed as said in many ways; multiple kinds of causes are investigated for the same thing; necessity is hypothetical rather than categorical. The innovation of the potentiality/actuality pair gives a whole extra dimension to all of this. The concrete comes to be teeming with alternatives, but without falling into arbitrariness. Things aren’t just what they are, full stop, and they don’t just follow a single, predetermined trajectory, but at the same time there is supple coherence and meaning everywhere. Potentiality itself is polymorphic; we don’t have just one potential, but many. But it is also bound to concrete reality.
Second, Aristotle puts actuality before potentiality, reversing the logical order of precedence implicitly followed by nearly everyone else, before and since. This has all sorts of implications. It directs our attention toward the concrete. It gives positive ethical value to concrete manifestation and particular being. It supersedes the arbitrary or random aspect of mere logical possibility, while still leaving flexibility in things through the additional dimension of potentiality. Potentiality is not abstract possibility.
Third, actuality is not factuality. It is through-and-through a normative concept of the realization of an end that may or may not be achieved. Since potentiality is defined by its relations to actuality, it acquires a normative aspect as well. Each potentiality is a capability for realizing a definite end, not just a general ability to do things. Thinking in terms of actuality and potentiality puts what Aristotle calls that-for-the sake-of-which and the good first in the order of explanation.
Reaching this point in my own modest textual commentary on the Metaphysics thus has a bit of the feeling of glimpsing the promised land. With such extraordinarily high expectations, the beginning of a more disciplined confrontation of the text of book Theta (IX) has been sobering. There are gaps between what I imagine it ought to say and what it does say, and I find the remainder of the text of the Metaphysics to be quite uneven. This may in part have to do with ancient editing of the manuscripts, and the loss of many more Aristotelian writings (see The Unity of Aristotle’s Metaphysics; Fortunes of Aristotle). But from internal references in the text, some of the issues seem to belong to the original.
I have several frustrations with the text of book Theta. In spite of the importance for Aristotle of conceptually putting actuality before potentiality, the account of potentiality is placed first in the text. Then for some reason he makes the choice to focus almost entirely on potentiality’s relation to the causing of motion as discussed in the Physics, even while acknowledging that this is “not the sense that is most useful for what we now want” (Sachs tr., p. 167). What we now want, in my opinion, is an account relating the original and distinctive aspects of potentiality and actuality to Aristotle’s original and distinctive view of that-for-the-sake-of-which and its ultimate relation to the good as first in the order of explanation. This ought to be the crown jewels of the whole Metaphysics. But the way it is presented, it falls short of what I would hope for. Later books partly make up for what is missing here, but on many points we are left to read between the lines. This leaves Aristotle’s overall message less clear than we might wish.
The Postmodern Peripatetic 