Class struggle is not only the conflict between wage labor and capital. When Marx speaks of Ireland, at that time a colony of Great Britain, he notes that here the "social question" appears as a "national question." According to Engels, "the first class oppression coincides with that of the female sex by the male." Thus, it concerns three major class struggles that are destined to radically question the division of labor as well as the relations of exploitation and oppression—on an international level, within a single country, and within a family. To explain the colossal upheavals in the transition to the 21st century, Losurdo finds the theory of class struggle more relevant than ever. This is in engagement with Jürgen Habermas, Hannah Arendt, Simone Weil, various currents of Marxism, and the post-Marxism of Negri and Zizek.