Natural law theory has been enjoying a significant revival in recent times. Led by Germain Grisez in the USA and John Finnis in the UK, one school of thinkers has been articulating a highly developed system of natural law built upon a sophisticated account of practical reasoning and a rich and flexible understanding of the human good. However, long-standing prejudices against old-style natural law among moral philosophers and Protestant ethicists, together with the new theory's appropriation by conservatives in the impassioned debate between the Vatican and dissenting theologians in the...