Book Reviews Review of John P. Lizza, ed., Potentiality: Metaphysical and Bioethical Dimensions 1 Reviewed by Jake Earl, Georgetown University Each of the 13 articles in this collection wrestles with intri- cate metaphysical and moral aspects of the widespread belief that a thing’s potential—what it could, would, might, or will be, but isn’t yet—matters for how we should treat that thing. As John Lizza explains in his lucid intro- duction (12), the articles are grouped into three parts according to their aims and theoretical constraints. In this review, I briefly summarize and offer some critical discus- sion of each part. Part I consists of five articles that engage with the metaphysics of potentiality and suggest some implications that concept might have for moral issues involving early human life. Mohan Matthen (“Aristotle’s Theory of Potentiality”) provides helpful interpretation and synthesis of Aristotle’s approach to potentiality, in particular his distinction between active potentiality (where changes are initiated within the thing that has the potential) and passive poten- tiality (where the changes are initiated elsewhere) (30). Matthen also illuminates the role played by potentiality in Aristotle’s views about essences and natural kinds (31), about the concepts of possibility and capacity (37–39), and about human nature and moral status (40–46). Jennifer McKitrick (“Dispositions and Potentialities”) argues that potentialities are best understood as kinds of dispositions (59), complex properties that involve, for instance, having a typical manifestation (e.g., a wine glass’s shattering on impact), being possessed without that typical manifestation actually manifesting (e.g., a wine glass’s not shattering when wine is poured into it), and so on (50). An interesting consequence of McKitrick’s argu- ment is that potentialities might be extrinsic or intrinsic (62–63), which (if true) could have interesting implications for ethical debates about the potential of frozen embryos that are unlikely to be implanted or fetuses that are likely to be aborted (65). In a brief piece, Joel Feinberg (“The Paradoxes of Potentiality”) offers some examples suggesting that our judgments about potentiality are highly context sensitive, and might be conditional on our evaluative background beliefs. Edward Covey (“Physical Possibility and Potential- ity in Ethics”) considers several varieties of possibility (log- ical vs. nomic, remote vs. proximate, absolute vs. actual), potentiality (as context-dependent possibility, capacity, or teleological potentiality), and ethical principles that put theoretical weight on these various notions. These two articles highlight the diversity of our intuitions about the metaphysics of potentiality, and suggest how this could pose a problem in ethical debates. The clearest takeaway from Part I is that we face a stark choice between the Aristotelian/Thomistic metaphysical approach described by Matthen (and Eberl in Part II) and the 20th-century Anglophone approach of McKitrick, Fein- berg, and Covey. And even though this choice of frame- works will be relevant throughout the remainder of the book, there is little guidance on why the reader should endorse one over the other. I don’t think this is a flaw of the volume, but rather just a consequence of its attempt to exhibit the role that a complicated metaphysical concept plays in equally complicated debates in bioethics. The papers are sufficiently well cited that the curious reader will have plenty of direction for additional research. Edward Langerak (“Abortion: Listening to the Mid- dle”) aids the transition between Parts I and II, arguing for a moderate position on the morality of abortion (all abor- tions are morally problematic, but especially so later in pregnancy) by deploying a potentiality principle: “If, in the normal course of its development, a being will acquire a person’s claim to life, then by virtue of that fact it already has some claim to life” (86). Part II consists of five articles that attempt to advance or resist potentiality prin- ciples like Langerak’s by staking out positions on moral Ó Jake Earl Address correspondence to Jake Earl, PhD Candidate, Department of Philosophy, Georgetown University, 37th and O Streets, NW, Washington, DC 20057, USA. E-mail: jce27@georgetown.edu 1. 2014, Baltimore, MD: Johns Hopkins University Press. 288 pp; $49.95 (paperback). W10 ajob The American Journal of Bioethics, 15(8): W10–W12, 2015 Published with license by Taylor & Francis ISSN: 1526-5161 print / 1536-0075 online DOI: 10.1080/15265161.2015.1048641