After Humanity is a guide to one of C. S. Lewis’s most widely admired but least accessible works, The Abolition of Man, which originated as a series of lectures on ethics that he delivered during the Second World War. These lectures tackle the thorny question of whether moral value is objective. When we say something is right or wrong, are we recognizing a reality outside ourselves, or merely reporting a subjective sentiment? Lewis addresses the matter from a purely philosophical standpoint, leaving theological matters to one side. He makes a powerful case against subjectivism, issuing an intellectual warning that, in our “post-truth” 21st century, has even more relevance than when he originally presented it.