Book Review Real Essentialism, by David S. Oderberg. New York, NY: Routledge, 2007. Pp. ix + 314. H/b £80.00, P/b £26.99. David Oderberg's Real Essentialism is an extended defence of the traditional Aristotelian idea that everything has an essence. Chapter one is a critique of what Oderberg calls 'contemporary essentialism', accounts of essentialism that attempt to analyse essence in terms of notions such as possibility and necessity. In Chapter two, Oderberg addresses criticisms of essentialism that originate with Quine, Popper, and Wittgenstein. Chapter three focuses on the epistemology of essence, arguing that we can come to know the real essences of things even though they may not be directly observable. Chapter four marks the section of the book wherein Oderberg presents his account of the structure of essence. This account is situated within a metaphysical framework of hylomorphism, the view (roughly) that all material objects consist of form (or actuality) and matter (or potentiality). Chapters five and six explore the connections between essence, existence, and identity. In Chapter seven, Oderberg discusses some features of his account of essence, including how the real essentialist treats accidents, properties, artifacts, and matters of constitution. In Chapters eight to ten, Oderberg applies his hylomorphic account of essence to life, species, and persons. In Chapter eight, Oderberg argues that the distinction between living and non-living things is that living things have a 'life principle or soul,' whereas non-living things do not (p. 194). Chapter nine is a defence of essence in the biological domain. Chapter ten is a defence of the claim that what distinguishes human beings from all other living creatures is that our essence is constituted by the form of rationality. Oderberg covers a tremendous amount of ground in Real Essentialism. Unfortunately, the ambitious scope of the book makes it hard for the author to cover the material in as much detail as it deserves. Early on in the book, for example, Oderberg claims that the structure of reality must be such that there are metaphysically substantive facts about resemblance. While I am sympathetic to this idea, I found it difficult to understand some of Oderberg's arguments. For instance, Oderberg gives the following reductio ad absurdum argument against 'evolutionary theories of our classificatory practices' (p. 44): If, as Quine claims, our 'sense of comparative similarity ... is presumably an evolutionary product of natural selection' (Quine 1969: p. 171), the problem is that Mind, Vol. 0 . 0 . 2010  Mind Association 2011 at U niv. of M assachusetts/A m herst Library on F ebruary 18, 2011 m ind.oxfordjournals.org D ow nloaded from our existence as beings capable of classification according to principles of comparative similarity is presupposed by our implementation of those principles. Hence the principles cannot be applied to ourselves since we have to exist before we can apply them. But if they do apply to ourselves, then they have been implemented without any creature to implement them. (pp. 44–5) This argument begins with the claim that 'our existence as beings capable of classification according to principles of comparative similarity is presupposed by our implementation of those principles'. How should we understand this? One might take it to mean that the fact that principles of similarity are implemented entails that there exists something that does the implementing. While this is certainly true, it does not seem to entail anything about whether we can apply such principles to ourselves. Suppose our sense of beauty is an 'evolutionary product of natural selection'. Presumably we do not want to conclude that we cannot apply our standards of beauty to ourselves. (This would make the tale of Narcissus hard to understand.) Alternatively, one might understand Oderberg as saying that if evolutionary theories of our classificatory practices are correct, then principles of classification are in some sense 'dependent' on us in a way that, say, principles of physics are not. But again it does not seem to follow that we cannot apply such principles to ourselves. Consider principles of politeness. They are dependent on us in the relevant sense. But we do not want to conclude that we cannot apply such principles to ourselves. I am not, of course, suggesting that either of these proposals is what Oderberg has in mind. But without further guidance, it is difficult to know how to understand the argument, and thus it is difficult to assess its merits. Elsewhere, Oderberg presents intriguing positions, but the cases he makes for them sometimes seem too hurried. For instance, consider Oderberg's argument that simple material objects are metaphysically impossible. (This view dovetails with Oderberg's belief that 'metaphysical atomism is false a priori' (p. 269).) Here is the argument: [T]he very idea of a material metaphysical simple makes no sense. If a material object were simple it would be unextended - but then in what sense would it be material? An extensionless point is not a something but a nothing, and so cannot be a locus for concepts, which are something. Further, extensionless points cannot have any constitutive relations to the extended ... (p. 253) This passage includes a number of contentious claims. One is the assertion that 'extensionless points cannot have any constitutive relations to the extended'. (Oderberg makes a similar claim in his criticism of the fourdimensionalist view of persistence, saying that the view is in danger of being 'reduce[d] to absurdity by invoking literally instantaneous object-stages that cannot give rise to any temporally extended object' (p. 117).) For simplicity, let us put aside nihilistic views of constitution, since nihilism is not Oderberg's main concern here. In that case, this claim seems to entail that a line cannot consist of infinitely many extensionless points. But standard 2 Book Review Mind, Vol. 0 . 0 . 2010  Mind Association 2011 at U niv. of M assachusetts/A m herst Library on F ebruary 18, 2011 m ind.oxfordjournals.org D ow nloaded from theories of geometry construe lines in just this way (cf. Adolf Grünbaum, Modern Science and Zeno's Paradoxes, Wesleyan University Press, 1967). Furthermore, it is unclear whether one can develop an adequate theory of the geometry of physical space that does not make use of extensionless points (for some work towards such a theory, see Arntzenius, 'Gunk, Topology, and Measure', in Oxford Studies in Metaphysics: Volume 4, ed. Dean Zimmerman, Oxford University Press, 2008; and see Grünbaum's Philosophical Problems of Space and Time, Knopf, 1963, for some reasons to be sceptical of the project). Given this, the reader would like to hear Oderberg's reasons for adopting this position. But Oderberg says little to motivate this view, and does not address any of the worries that have been raised about it. This is disappointing, as there is no doubt that Oderberg has interesting thoughts on the subject to share. Another contentious claim in the argument above is that a simple material object must be unextended. This too is controversial, and many of Oderberg's contemporaries have argued against it (for some discussion, see: Josh Parsons, 'Must a four-dimensionalist believe in temporal parts?' The Monist, 83 (2000), pp. 399–418; Kris McDaniel, 'Extended Simples', Philosophical Studies 133 (2007), pp. 131–41; Ted Sider, Four-Dimensionalism, Oxford University Press, 2001; inter alia). It would have been helpful to the reader if Oderberg had provided reasons in favour of adopting this premiss, and had engaged with the literature on this topic. In sum, Oderberg's Real Essentialism is a thought-provoking and wide-ranging book arguing for the intriguing thesis that essence is to be situated within a hylomorphic metaphysical framework. In his attempt to cover so much ground, however, Oderberg often fails to fill in the details of his arguments. This leaves one unable to engage with the interesting subject matter of Oderberg's work as much as one would have liked. M. EDDONDepartment of Philosophy University of Massachusetts - Amherst 357 Bartlett Hall 130 Hicks Way Amherst, MA 01003-9269 USA doi:10.1093/mind/fzq086 Book Review 3 Mind, Vol. 0 . 0 . 2010  Mind Association 2011 at U niv. of M assachusetts/A m herst Library on F ebruary 18, 2011 m ind.oxfordjournals.org D ow nloaded from