He is the author of *Are Species Real?* (Palgrave, 2013), has co-edited a number of volumes on metaphysics and the philosophy of science (including, from MIT Press, *Carving Nature at its Joints* (2011), *The Environment: Science and Ethics* (2012), and from Oxford University Press *Metaphysics and the Philosophy of Science*). He has written widely on metaphysics, philosophy of biology, and social epistemology. His recent essay, “Natural Kindness” won the 2015 Karl Popper Prize from the British Society for the Philosophy of Science. He is currently working on two book projects: one focusing on biological classification at various levels of generality and another, co-authored with Matthew Barker, on the role that norms play in scientific classification in general.