Since the dawn of culture, philosophers, theologians, and social theorists have argued over the correct way to determine moral action. Is it based on reason, outcomes, or the word of God? Common to nearly all was the belief that there was a right answer. Churches, courts, and constitutions were built on the assumption that morality was discovered and not invented. But increasingly critics reject this outlook altogether. Competing accounts diverge so radically that no single theory can plausibly claim to be morally correct. Practices once upheld as moral are now condemned as barbaric. The Greeks thought slavery natural and just, Hitler described the holocaust as a 'moral imperative', and just a hundred years ago the US Supreme Court ruled forced sterilisation of the disabled a state obligation.

Should we abandon the idea that there is a correct way to determine good and evil? Do moral rules, codes and principles always result in perverse outcomes in some scenarios? Or is it essential to be able to call on a single principle to determine right action, and if so, what is it?

Critical race theorist Tommy Curry, controversial author of Gaza's Gravediggers Norman Finkelstein, and Labour life peer Thangam Debbonaire debate morality.