The Class Struggle (Erfurt Program)

The Erfurt Program Explained in its Fundamental Part (German: Das Erfurter Programm in seinem grundsätzlichen Theil erläutert), commonly known as The Class Struggle (Erfurt Program), is an 1892 book by the Marxist theoretician Karl Kautsky. It is a commentary on the 1891 Erfurt Program of the Social Democratic Party of Germany (SPD), for which Kautsky was a principal author. The book became one of the most widely read and influential works of Marxism, serving as a popular and systematic exposition of the theory for an international audience. It was Kautsky's first major work published without direct guidance from his mentor, Friedrich Engels, and cemented his reputation as the leading theoretician of the Second International.

The book analyzes the development of capitalism, the nature of the future socialist "commonwealth," and the tactics for achieving it. It outlines Kautsky's synthesis of Marxist theory, blending an emphasis on the historical inevitability of social revolution, rooted in economic development, with the necessity of conscious, organized political action by the proletariat. While Kautsky's prose reflected the pressures of internal party politics in Wilhelmine Germany, the work was widely received as a revolutionary document.