The theological doctrine of biblical inerrancy is the intellectual basis for modern creation science. Yet Benjamin Breckinridge Warfield of Princeton Theological Seminary, the theologian who more than any other defined modern biblical inerrancy, was throughout his life open to the possibility of evolution and at some points an advocate of the theory. Throughout a long career Warfield published a number of major papers on these subjects, including studies of Darwin's religious life, on the theological importance of the age of humanity (none) and the unity of the human species (much), and on Calvin's understanding of creation as proto-evolutionary. He also was an engaged reviewer of many of his era's important books by scientists, theologians, and historians who wrote on scientific research in relation to traditional Christianity. Exploration of Warfield's writing on science generally and evolution in particular retrieves for historical consideration an important defender of mediating positions in the supposed war between science and religion.