Standard approaches to moral puzzles rest on a shared metaphysical premise: that morality is timeless, written into the fabric of the universe. What has been largely absent from the literature is a systematic contractarian response to these puzzles – an absence that, Malcolm Murray argues, continues to impoverish the field and foreclose entire areas of study.

In Murray’s contractarian view, morality is not a set of enduring truths but the outcome of human evolution and natural selection. This social contract, a system of rules that rational, self-interested agents agree to follow because it enables a safer, more co-operative social life, highlights the difference between idealized moral theories and the real-world applications that often fall short of those ideals. In elegant, entertaining prose Moral Puzzles ventures beyond the popular understanding of morality as a natural product, revisiting canonical problems in moral philosophy with striking results. Murray argues, for example, that diverting a trolley to kill one person rather than five is unjustified without that person’s consent, and that disgust toward consensual acts such as incest cannot by itself support condemnation.

Moral Puzzles also confronts challenges to contractarianism itself, including the is-ought problem – whether prescriptive statements (what ought to be) can be made based on descriptive statements (what is) – and classic thought experiments such as the ring of Gyges – whether people, when free from the consequences of their unjust actions, will still act justly. Taken together, these analyses invite readers to rediscover the central puzzles of moral theory through fresh arguments and interpretations.