 Socrates does not take on Protagoras’ claims directly. Instead, he takes another tack and engages Protagoras in three rounds. In the first round, he asks about the  unity of virtues,  arguing for the unity of justice and piety, of wisdom and self-control, and of self-control and justice (328d–334c). The series of arguments is inconclusive; Protagoras’ consent to them is grudging, and scholarly opinion is divided as to their soundness. The series breaks down over the issue of sound-mindedness and injustice. It would appear that one could apply a sound mind to unjust actions (say, by not letting sensual pleasures distract one from a life of theft). But Socrates seems about to say that both justice and sound-mindedness aim at what is beneficial to human beings, and this provokes Protagoras to affirm the incompleteness of the word “advantageous”: different things are advantageous to different species, and in different applications.