Book excerpt: A theological history of consequentialism and a fresh agenda for teleological ethics. Consequentialism—the notion that we can judge an action by its effects alone—has been among the most influential approaches to ethics and public policy in the Anglophone world for more than two centuries. In The Best Effect, Ryan Darr argues that consequentialist ethics is not as secular or as rational as it is often assumed to be. Instead, Darr describes the emergence of consequentialism in the seventeenth century as a theological and cosmological vision and traces its intellectual development and eventual secularization across several centuries. The Best Effect reveals how contemporary consequentialism continues to bear traces of its history and proposes in its place a more expansive vision for teleological ethics.