Natural Categories and Human Kinds
Classification in the Natural and Social Sciences

"… [Natural Categories and Human Kinds] is to my mind the most up-to-date, comprehensive, and interesting book-length treatment of natural kinds available today. Both newcomers to this area of inquiry and seasoned veterans will doubtless benefit from its study. Khalidi’s straightforward prose and careful argument makes the book a pleasure to read and think about; his patient stage-setting and summary make it an excellent option for advanced undergraduate courses in the philosophy of science."
Matthew H. Slater, British Journal for the Philosophy of Science

"… this seems to me the best general treatment of natural kinds for many years. It provides an important contribution to the general naturalistic trend of contemporary philosophy of science. It is always clearly written and clearly argued, and it would provide an excellent basis for seminars on its topic at levels up to the postgraduate … I suspect it will reinvigorate discussion of what will continue to be seen as a central topic in philosophy of science and metaphysics."
John Dupré, Mind

"… Khalidi's book in several respects is an important addition to the literature on natural kinds, and required reading for anyone working on the topic. Foremost, it introduces a novel account of kinds that … is a considerable step forward from the popular 'homeostatic property cluster' account and should make a good starting point for further work. Also, it is a rich resource of examples of putative natural kinds from very diverse areas of natural and social science. Finally, the book provides excellent discussions of the spectrum of philosophical issues that occupy center stage in the recent literature on natural kinds, and provides convincing rebuttals to arguments that say natural kinds are not found in the special sciences."
Thomas Reydon, Metascience

"… let me commend Khalidi's book to readers interested in scientific taxonomy and natural kinds. It does an excellent job both of working through general, conceptual issues to craft a useful philosophical conception and of deploying that conception to think through a wide range of specific examples."
P. D. Magnus, Studies in History and Philosophy of Biological and Biomedical Sciences

"The book has meticulous arguments for the theses proposed and meticulous considerations of the possible counterarguments and objections. Moreover, [it] is concisely and densely written. The user-friendly Preface contains an overview of the argument in each of the six chapters … [this] book is of great value in providing a novel approach to naturalism and a theory of scientific realism that involves enlightening discussions of various theories and cases in the sciences. Moreover, those who have alternative accounts of naturalism that are reductionist, that reject natural kinds, or that reject causality need to take seriously the arguments for natural kinds, causation, and scientific realism that are presented in this book."
Sheldon Richmond, Philosophy of the Social Sciences

"Philosophers and scientists on either side of the fence, whether of naturalist or social constructionist persuasion, will find plenty of material to sink their teeth into in Khalidi's delightfully argued and wide-ranging treatment of natural kinds … We can … only commend Khalidi for his valiant attempt at restoring the notion of natural kinds to the central place within philosophy where it belongs."
Georg Theiner, Journal for General Philosophy of Science