Muhammad Ali Khalidi is Associate Professor of Philosophy at York University, Toronto.

'Muhammad Ali Khalidi has given us the best articulated treatment to date of a flexible, naturalistic approach to natural kinds. His wide-ranging treatment of kinds in the special sciences is especially noteworthy. Moreover, the book is so well written that it works well as an introduction to this difficult topic area as well as providing plenty of stimulation for seasoned professionals. It will surely be at the center of future discussion among scientific philosophers and philosophical scientists.' Tom Nickles, University of Nevada, Reno

• Preface; 1. Realism and essentialism about kinds; 2. The naturalness of kinds; 3. Kinds in the special sciences; 4. Kinds in the biological and social sciences; 5. Kinds of natural kinds; 6. Naturalising kinds.

Muhammad Ali Khalidi is Associate Professor of Philosophy at York University, Toronto.

'Muhammad Ali Khalidi has given us the best articulated treatment to date of a flexible, naturalistic approach to natural kinds. His wide-ranging treatment of kinds in the special sciences is especially noteworthy. Moreover, the book is so well written that it works well as an introduction to this difficult topic area as well as providing plenty of stimulation for seasoned professionals. It will surely be at the center of future discussion among scientific philosophers and philosophical scientists.' Tom Nickles, University of Nevada, Reno

• Preface; 1. Realism and essentialism about kinds; 2. The naturalness of kinds; 3. Kinds in the special sciences; 4. Kinds in the biological and social sciences; 5. Kinds of natural kinds; 6. Naturalising kinds.

Muhammad Ali Khalidi is Associate Professor of Philosophy at York University, Toronto.

'Muhammad Ali Khalidi has given us the best articulated treatment to date of a flexible, naturalistic approach to natural kinds. His wide-ranging treatment of kinds in the special sciences is especially noteworthy. Moreover, the book is so well written that it works well as an introduction to this difficult topic area as well as providing plenty of stimulation for seasoned professionals. It will surely be at the center of future discussion among scientific philosophers and philosophical scientists.' Tom Nickles, University of Nevada, Reno

• Preface; 1. Realism and essentialism about kinds; 2. The naturalness of kinds; 3. Kinds in the special sciences; 4. Kinds in the biological and social sciences; 5. Kinds of natural kinds; 6. Naturalising kinds.