Journal of the History of Philosophy

In this monograph, Sentesy defends the revolutionary Aristotelian claim that change is. Change is, insofar as it exists and can be defined; it has identifiable aspects and is subject to analysis, as much as anything else that is. The contradictory claim would be, of course, that change is not—that change is the opposite of being, a becoming that itself is nothing. The fundamental claim of this book is that such conceptions are mistaken, that Aristotle has an ontology of change that accounts for it as both real and existent, and also that the possibility of describing said ontology of change is itself evidence for the claim that change is. Sentesy writes, "In showing what change is, Aristotle also shows that it exists" (48).

The concept of change the author defends in the early chapters is that change, like being, is composite. Sentesy identifies three elements of change, each of which he describes as a "phenomenal element discovered in the articulate experience of change" (29): the form (eidos/morphe¯), its privation (enantion/stere¯sis), and the underlying material (hupokeimenon/hule¯). These "aspects of change" (39) make it possible to speak about change without rendering it a mix of being and nonbeing (which Sentesy aims to avoid). Relying mainly on the Physics, the ultimate definition of change the author defends is that it is a completion of a potency—the entelecheia of a dunamis. Sentesy notes that in order to avoid the threat of nonbeing's reinserting itself into the ontology of change, we must avoid some common tendencies—that of equating actuality with being, and then opposing actuality and potency (which would result in the equation of potency with nonbeing). Sentesy writes that potency, instead, must be a "distinct and independent way of being" (87). On my reading, this is Sentesy's boldest claim.

The claim that potency is a way of being appears unintuitive, because we tend to describe things in potency according to the fact that they are not what they are in potency—to be something in potency is to be not that thing—for it is only by virtue of the fact that I am not a lawyer that I am a lawyer in potency. But in support of Sentesy's interpretation, I point to what Aristotle says at Met. IX.3, 1047b1–2: τῶν γὰρ μὴ ὄντων ἔνια δυνάμει ἐστίν· οὐκ ἔστι δέ, ὅτι οὐκ ἐντελεχείᾳ ἐστίν. The implication is that potency's nonbeing is only a relative nonbeing (a nonbeing relative to actuality, i.e. not being an actuality). Not everything that is not [End Page 512] something is in potency that something (Met. IX.7). That is to say, it is not by virtue of the fact that I am not a lawyer that I am in potency a lawyer—it is by virtue of the fact that I am a human capable of attending law school. When formulated such, the threat of nonbeing disappears. (By much the same reasoning, "privation" does not count as nonbeing in the above description of the aspects of change.) The interpretation becomes more intuitive if we allow, as Sentesy does, that potency-activity is an analogue of matter-form, for the opposition of matter to form is less likely to be described as a relation of nonbeing to being, and we are less likely to say of matter than we are of potency that it in no way exists.

The rest of the book is devoted to analyses of the aspects of change—potency, energeia and entelecheia, genesis and epigenesis, and, of particular interest, an analysis of sources (archai). There is a compelling argument toward the redemption of teleology, for insofar as there is movement from potency to actuality, there is a telos involved—"dunamis points toward entelecheia" (62). The etymology supports this argument, just because the word we are translating as "actuality" is entelecheia, or the "in-telos-having," which is the subject of Sentesy's third chapter (along with entelecheia's distinction from and relation to energeia, which we also translate as "actuality").

The book's rigor does...