Boris Johnson has described a chilling phone call in which Vladimir Putin threatened him with a missile strike in the run-up to Russia's invasion of Ukraine. Almost a year on from the start of the war, it’s tempting to see it as a clear-cut conflict between good and evil; Putin the malign aggressor bent on destruction and conquest, Zelensky the courageous defender of liberty and his country. It may be true, or at least substantially so, but is it helpful? Seeing events through the prism of good and evil enables us to make moral judgements and define what we value. But it can also brush aside the ambiguities of complex situations and de-humanise both those we deem evil, and those we regard as good. Plato and St Augustine thought they were not opposites; that evil was the absence of good, a lack of moral imagination. Psychologists might prefer to dispense with the term ‘evil’ altogether, seeing it as human behaviour to be explained and understood. Does evil exist? If so, what is it? And how should we deal with it? With Ed Condon, Professor Scott Atran, Professor Lars Svendsen and Professor Tony Maden Producer Dan Tierney