In Rameau’s Nephew, Lui (Rameau’s nephew) and Moi (Diderot) engage in a combative conversation. The work is a totality of contradictions. Lui insists upon what he believes to be true and Moi objects that the exact opposite is right. Lui is a self-admitted parasite upon society who takes advantage of everyone and everything that he can. He admits to having taught his son that money is more important than anything else and to mourning his deceased wife because he could have profited by prostituting her. Lui insists that his lifestyle is morally correct. Moi, who is the embodiment of bourgeois morality, is appalled by Lui and vehemently objects to his assertions. Lui and Moi are both strong combatants, and Diderot does not permit either one a decisive victory. This ambiguity makes the dialogue an inquiry into morality that never finds an answer.

While neither Lui nor Moi can claim a victory, they do lead each other into a state of change, of becoming less of what they were. The character of Lui also undergoes startling physical change as he contorts himself in the most outlandish fashion, acting out what he says. Lui is like an actor, creating characters by his gestures and physical contortions. Just as Lui contorts himself to assume the various individuals he talks about, he also shapes himself into whatever he needs to be to profit from social opportunity. Lui’s explanation of his relationship to the society in which he lives enables Diderot to satirize a number of his enemies in the novel.