This book is about how logic relates to evolutionary theory. It is a study in the biology of logic. It attempts to outline a theory of rationality in which logical law emerges as an intrinsic aspect of evolutionary biology, part of it and inseparable from it. It aspires to join the ideas of logic to evolutionary theory in such a way as to provide unified foundations for an evolutionary science of Reason.

An understanding of modern evolutionary explanation and sympathy with its aims has been assumed throughout. A prior acquaintance with the elements of symbolic logic and probability theory has been assumed as well, and some familiarity with decision theory would be desirable. Beyond that, it is my hope that philosophers of science, logicians, evolutionists, cognitive scientists, and others, will find the exposition readable.

The mathematics has been kept to a minimum. The exception is an important appendix which sets forth in mathematical detail a critical portion of the underlying formal development. My effort has been to make the theory as clear as possible, both conceptually and mathematically, with the heavier math kept separate for those who might wish to study the theory in greater depth.

The work owes much to many people. Of special note is the fact that one of the evolutionary models receiving attention (Model 5) resulted from a collaboration with Professor Robert Kaplan, now of Reed College, to whom I am deeply indebted for numerous evolutionary insights. I am grateful to Professors Ernest Adams, Bill Maron, Steven Stearns, and several referees for their valuable suggestions and criticisms of the manuscript.