In one of his arguments for taking compassion to be the basis of morality, Schopenhauer offers a thought experiment involving two characters: Titus and Caius. The 'Titus Argument,' as I call it, has been misunderstood by many of Schopenhauer's readers, but is, I argue, worthy of attention by contemporary ethicists and metaethicists. In this chapter, I clarify the argument's structure, methodology, and its key philosophical move, drawing comparisons with Newton's experimental methodology in optics and Raimond Gaita's moral parodies.