J. Baird Callicott is a founder and seminal thinker in the modern field of environmental philosophy. He is best known as the leading contemporary exponent of Aldo Leopold's land ethic, not only interpreting Leopold's original works but also applying the reasoning of the land ethic to modern resource issues such as wilderness designation and biodiversity protection.

Callicott's 1987 edited volume, Companion to A Sand County Almanac, is the first interpretive and critical discussion of Leopold's classic work. His 1989 collection of essays, In Defense of the Land Ethic, explores the intellectual foundations and development of Leopold's ecological and philosophical insights and their ultimate union in his later works. In 1991 Callicott, with Susan L. Flader, introduced to the public the best of Leopold's remaining unpublished and uncollected literary and philosophical legacy in a collection entitled The River of the...