The Aristotelian Tradition of Natural Kinds & Its Demise by Stewart Umphrey (review)

Umphrey's prior book, Natural Kinds and Genesis, discusses topically the questions "What is a natural kind?" and "Are there any natural kinds?"; this present volume looks at the history of these questions from early Greek poetry to Darwin. Together, the two books are meant to pave the way to a renewal of natural philosophy in the face of a double threat: the claim that natural kinds depend on our way of thinking and speaking, and the claim that philosophy without modern science would be blind to the empirical world as it really is.

Rather than pursue a single central thesis, the book recounts the origins and career of the idea of natural kinds. This history illustrates three theses of importance to natural philosophers: (1) that no philosophical claim concerning natural kinds occurs in a historical vacuum; (2) that there have been two major revolutions in the history of natural philosophy, one when Aristotle replaced Presocratic understandings of nature with his biocentric and eido-centric conception of nature, the other when Galileo replaced Aristotle's conceptions with a nomo-centric and mechanocentric conception of nature; and (3) that natural philosophy is always in crisis. The book describes four crises in natural philosophy's history. Parmenides introduced the first by asserting that natural things are mere seemings. Plato's Socrates brought on the second by proposing that the study of nature is a distraction from man's proper study of the beautiful, the just, the good, the soul, and the city. The third crisis was ushered in by the medieval Schoolmen who held that natural philosophy must subordinate itself to the authority of church doctrine and to the authority of Aristotle's physics. Kant initiated a fourth crisis by insisting that Newtonian physics could be truly scientific only if we suppose that nature, though empirically real, is transcendentally ideal, as a consequence of which natural philosophy must lose its independent role and become subordinate to the authority of scientific theory. Though these crises are important moments in the book, the chapters are distinguished not by these but by various figures or groups of related figures (Presocratic philosophers, Plato, Aristotle, Aquinas/Ockham, Galileo/Descartes, Locke/Leibniz/Kant, and finally Darwin) who have loomed large in the history of thought about natural kinds.

The book is not easy reading. Especially chewy is the prologue, thanks to its dense and technical summary of the author's prior book. The demanding nature of the rest of the book is a function of the difficulty of the matter, of the author's evident zeal for precision, and of the diversity of things he is doing (for example, recounting a history, explaining how its stages interact, critiquing some of the thinkers who shaped it, and rejecting facile critiques of them).

In addition to tracing the history of thought about natural kinds, the book has other goods to offer. For example, the author points out five differences between Plato's Socrates and the Eleatic stranger, two of Plato's lead characters whose similarities might cause us to overlook their important and illuminating dissimilarities. The book can also stand as a model for how natural philosophers ought to engage not only classical and modern science, but also ancient and medieval thought and modern and contemporary philosophy. Umphrey, who rightly calls Aristotle manywayed (as opposed to a system-builder or someone with a one-size-fits-all method), seems to be rather Odyssean himself.

I have some reservations about the book, two of which I will mention here. First, some of its less defended assertions about who thought what are eminently disputable (for example, that Aristotle thought there were many distinct beings each of which is self-thinking thought, and that the human soul ceases to exist at death), and a few are so infelicitously formulated it is hard not to see them as confusions (for example, that Aquinas thought that you do not cease to...