Terrorism and Communism: A Reply to Karl Kautsky (German: Terrorismus und Kommunismus: Anti-Kautsky; Russian: Терроризм и Коммунизм, Terrorizm i Kommunizm) is a book by Soviet Communist Party leader Leon Trotsky.

Trotsky's book, the first English edition of which bore the title The Defense of Terrorism, dismisses the notion of parliamentary democracy to govern Soviet Russia and defends the use of force against opponents of the revolution by the dictatorship of the proletariat and working class masses.

[1] Kautsky's pamphlet, Die Diktatur des Proletariats (The Dictatorship of the Proletariat), asserted that the only way to control the growth of bureaucracy and militarism and to defend the rights of political dissidents was through parliamentary democracy based upon free elections and that V. I. Lenin and his political associates had blundered badly by departing from democratic practice in favor of a restricted electorate and the use of extra-parliamentary force.

[4] Lenin railed against Kautsky's pamphlet as the "most lucid example of that utter and ignominious bankruptcy of the Second International about which honest socialists in all countries have been talking for a long time.

[11] After expounding at length upon the dialectic of revolutionary violence in the historic French context, Kautsky turned his focus in the final section of Terrorism and Communism to "The Communists at Work.

[14] The Bolsheviks made calculated use of this elemental force, in Kautsky's view, "introducing anarchy in the country" in exchange for "a completely free hand in the towns in which they had already likewise won over the working classes.

"[18]Kautsky singled out Bolshevik leader Leon Trotsky for specific criticism, upbraiding him for having seized power despite an admitted foreknowledge that the Russian working class and the revolutionary intelligentsia acting in its name had lacked "the necessary organisation, the necessary discipline, and the necessary historical education" to successfully establish a new economic and political regime.

The book was written, Trotsky remembered in 1935, inside a coach attached to his armored train during the tumultuous Polish Campaign of the Russian Civil War.

"So long as the class struggle flowed between the peaceful shores of parliamentarism, Kautsky, like thousands of others, indulged himself in the luxury of revolutionary criticism and bold perspectives: in practice these did not bind him to anything.

"[24] Akin to the principle of self-defense, Trotsky argued in Terrorism and Communism that "the taking of human life was not only a necessary evil but an expedient act in time of revolution," in Knei-Paz's view.

[24] Trotsky justified the use of terror against the revolution's enemies by asserting that its use was directed and controlled by the working class itself rather than by a small circle of individuals in a political party.

"[31] Parliamentarism was a cloak and a fiction employed to mask the rule of capitalist societies by vested economic interests, in Trotsky's view, whereas the dictatorship of the proletariat was able to make use of organized state power by the working class to crush its opponents and to pave the way for social transformation.

[35] In subsequent decades the book has seen print in Arabic, Chinese, Czech, Danish, Greek, Japanese, Serbo-Croatian, and Turkish, with multiple editions in some of the aforementioned languages.

In it Kautsky noted the existence of drought and famine in Soviet Russia, a deadly situation which he asserted was exacerbated by a dysfunctional form of agrarian organization, transportation problems resulting the disruption of the national railway system which impeded the importation of food from non-famine areas, and bureaucratic paralysis.

Conversely, Knei-Paz contrasted this use of terror with the methods adopted by Stalin during the Great Purge which was taken to an unprecedented scale and became a permanent feature of the Soviet system.