The heart of existentialism is the doctrine of radical freedom. The human condition, we are told, is one of inescapable freedom (though not just this), and hence inescapable responsibility, which is to say an unremitting responsibility to choose our own values and commit ourselves to them. This idea conflicts sharply with familiar ways of speaking. We often say things like “I cannot come because I must…,” and the “cannot” and “must” signify necessities which constrain our choices and our actions. They rule out courses of action as impossible. But if Sartre is right,