This raises the question of what causes some ideas to become important, such as equality, and others to fall out of favour, such as slavery or the diving right of kings. Marx accounts for this historical change by arguing that ideas are attached to the interests of social classes such as the workers or the capitalists. These class interests gave rise to the great "isms" of ideological politics, from communism and socialism to consetvatism and fascism. The social classes of Marx are not the only source of ideologocal politics. Many recent political ideas have also emerged from developments within liberalism, conservatism, socialism, and nationalism.