 This is also the challenge posed by the sophist Antiphon, in the surviving fragments of his discussion of justice in On Truth (see Pendrick 2002 for the texts of Antiphon, and Gagarin and Woodruff 1995 or Dillon and Gergel 2003 for translation). Antiphon argues that justice is only ever a matter of following the laws of one’s own community; and that there is no good reason for anyone to obey those laws when they can break them without fear of detection and punishment. For nature too has its laws, which conflict with those of society, and violation of these is punished infallibly. Antiphon’s text and meaning are unclear at some crucial points, but the idea seems to be that the laws of society require us to act against our own interests, by constraining our animal natures and limiting our natural desires and pleasures; and that it is foolish to obey these laws when we can get away with following nature instead. Without wanting to deny the existence of other contemporary figures working similar terrain, we can easily read Callicles, Thrasymachus, and Glaucon as Plato’s disentangling and disambiguation of Antiphon’s ideas into three possible positions, distinguished to clarify the various philosophical forms that a broadly immoralist stance might take. Thrasymachus represents the essentially negative, cynical, and debunking side of the immoralist stance, grounded in empirical observations of the ways of the world. At the same time his idealization of the ‘real ruler’ suggests that this is an unstable and incomplete position, liable to progress to a Calliclean ‘heroic’ form of immoralism. Callicles represents immoralism as a new morality, dependent on the contrasts between nature and convention and between the strong and the weak. Glaucon shows that the immoralist challenge has no need of the latter (nor, for that matter, of Thrasymachus’ ideal of the real ruler). Immoralism is for everybody: we are all complicit in the social compact which establishes law as a brake on self-interest, and we all have reason to cheat on it when we can. This, Plato’s presentation suggests, is ultimately the most challenging form of the immoralist stance; and it is probably the closest to its historical original in Antiphon himself. Whether the whole argument of the Republic suffices to defeat it remains a matter of live philosophical debate.