In Natural Kinds and Genesis: The Classification of Material Entities, Stewart Umphrey raises and answers two questions: What is it to be a natural kind? And are there in fact any natural kinds? First, using the everyday understanding of things, he argues that natural kinds may be understood as classes or as types, and that the members or tokens of such kinds are individual continuants. A continuant is essentially a being-in-becoming, a material thing which changes and yet remains the same, in virtue of its nature or essence, as long as it exists. In the primary sense of the term, then, a natural kind is a class whose members closely resemble one another substantially, in virtue of their essences. Alternatively, it is a type whose tokens exemplify it in virtue of their essences. To answer the second question, one must make use of relevant scientific theories as well. Umphrey agrees with scientific essentialists that there are natural kinds, but he argues that most of the chemical, physical, and biological kinds posited in current theories are not natural kinds in the primary sense of the term. The natural-kinds realism he affirms is thus quite restricted: it requires the existence of enduring things which closely resemble one another in virtue of their essences, and such things exist, apparently, only if they have come into being, or emerged, in the course of symmetry-breaking events. Natural Kinds and Genesis will be of interest to philosophers of science and to those interested in the metaphysics of natural kinds and their members.

Wherever we look, we notice complexity. Philosophically, the concept constitutes a tangled web of problems, in theory as well as daily life. Complexity and Analysis is a meticulous rendering of these problems, tackling the seldom considered nature of complexity that confronts ontological analysts and holists alike. Stewart Umphrey expertly describes the limits of analysis as they have come to light within mathematics, the natural sciences, and analytic philosophy, explaining how Aristotle came upon, and sought to move beyond, the limits of ontological analysis. In trying to understand any complex entity, Umphrey argues, one succeeds in meeting the criterion of metaphysical adequacy only if one fails to meet the crietrion of epistemological adequacy. Ranging across an array of subjects including Kantian and Hegelian idealism, this book provides a superb account of how our own complexity presents not only theoretical problems, but ethical and political dilemmas of great practical significance.

There are two great traditions of natural-kinds realism: the modern, instituted by Mill and elaborated by Venn, Peirce, Kripke, Putnam, Boyd, and others; and the ancient, instituted by Aristotle, elaborated by the "medieval" Aristotelians, and eventually overthrown by Galilean and Newtonian physicists, by Locke, Leibniz, and Kant, and by Darwin. Whereas the former tradition has lately received the close attention it deserves, the latter has not. The Aristotelian Tradition of Natural Kinds and its Demise is meant to fill this gap. The volume's theme is the emergence of Aristotle's account of species, what Schoolmen such as Thomas Aquinas and William of Ockham did with this account, and the tacit if not explicit rejection of all such accounts in modern scientific theory. By tracing this history Stewart Umphrey shows that there have been not one but two relevant "scientific revolutions" or "paradigm shifts" in the history of natural philosophy. The first, brought about by Aristotle, may be viewed as a renewal of Presocratic natural philosophy in the light of Socrates's "second sailing" and his insistence that we attend to what is first for us. It features an eido-centric conception of living organisms and other enduring things, and strongly resists any reduction of physics to mathematics. The second revolution, brought about by seventeenth-century physics, features a nomo-centric view according to which what is fundamental in nature are not enduring individuals and their kinds, as we commonly suppose, but rather certain mathematizable relations among varying physical quantities. Umphrey examines and compares these two very different ways of understanding the natural order.