The term "Don Juan" has become synonymous with "libertine" or "prolific lover of women." In his preface to Man and Superman, George Bernard Shaw denies that this is the essence of the character. In most versions of the story, including Mozart's, which seems to have had the most direct influence on Shaw, Don Juan is always boasting about the number of women he has seduced. For Shaw, however, the most important aspect of his personality is his cynicism, his refusal to pay homage to the conventions of society. The title of the play makes it obvious that Shaw was thinking of Nietzsche when he wrote it, and thinking in particular that the man who overcame the petty moral foibles of his age would be a Nietzschean superman.
Jack Tanner is a modern-day Don Juan because he is a moral nihilist. He is more sophisticated than the original because he does not focus on the sheer number of women he has seduced, but he has no moral ideals about marriage, monogamy or purity. In particular, he is resistant to and repulsed by the idea of romantic love, which he regards as a way of entrapping the independent man into a life of respectable drudgery. Tanner is not just a modern-day Don Juan, but a specifically Shavian one. Mozart's Don Giovanni and other early incarnations of the character were simple libertines, who pursued pleasure because they enjoyed it. Tanner has made his selfishness into a philosophy.