The philosophy of biology is one of the most exciting new areas in the field of philosophy and one that is attracting much attention from working scientists. This Companion, edited by two of the founders of the field, includes newly commissioned essays by senior scholars and up-and-coming younger scholars who collectively examine the main areas of the subject - the nature of evolutionary theory, classification, teleology and function, ecology, and the problematic relationship between biology and religion, among other topics. Up-to-date and comprehensive in its coverage, this unique volume will be of interest not only to professional philosophers but also to students in the humanities and researchers in the life sciences and related areas of inquiry.