Cosmos of Duty ... remains a must-have book for anyone interested by Sidgwick's moral philosophy. It is a detailed and rigorous study of Sidgwick's Methods. Crisp's personal insights may not convince all. But I have little doubt that all will find them insightful and inspiring.
Christophe Salvat, Revue des livres
Roger Crisp's penetrating and elegantly composed book is in part designed to demonstrate which of Sidgwick's views qualify, in Crisp's estimation, as true and important.
Anthony Skelton, Notre Dame Philosophical Reviews
The career of Oxford philosopher Roger Crisp has produced a wonderfully rich yield of elegant, lucid philosophizing that combines in a rare mix historical erudition and brilliant, creative, and highly interdisciplinary ethical argument . . .The subtlety and boldness of Crisp's defense of Sidgwick's better hedonistic angels is matched only by his similar sympathetic re-envisionings of Sidgwick's use of the term 'reasons,' dualism of practical reason, and potential for a makeover allowing for the insights of Ross on prima facie duties. Sidgwick could not have asked for a better tribute.
Bart Schultz, Journal of the History of Philosophy