Tim the terrorist: We have Tim the terrorist in custody, and we know that he knows where the bomb is that his group have secretly planted somewhere in central London, and we know that if we torture him hard enough he will reliably tell us where it is in time for us to defuse it, and we know that there is no other way of getting him to tell us, and we know that if we don't defuse it the bomb will kill thousands of innocent people. So: what to do?