The term scientific socialism was used by Friedrich Engels to characterize the doctrines that he and Karl Marx developed and distinguish them from other socialist doctrines, which he dismissed as utopian socialism. Engels regarded the Marx-Engels doctrines as scientific in that they laid bare the secret of capitalism through the discovery of surplus value, and explained (with a theory known in the USSR as historical materialism) how capitalism would inevitably be overthrown and replaced by socialism. The concept "scientific socialism" made Marxist doctrines more attractive to many than rival socialist doctrines by suggesting that equality and the end of exploitation were not only desirable but also inevitable.
Scientific socialism was introduced to Russia in the late ninenteenth century. After the Bolshevik victory in the civil war, scientific socialism became part of the official ideology of the USSR. The term itself was frequently used loosely to designate a doctrine concerning the development of a Soviet type of society. Much of the actual content of the doctrine varied over time in accordance with the concrete policies of the Soviet state.
Socialism as a comprehensive social system failed to spread to the advanced capitalist countries (although "pension fund socialism," the growth of government welfare and regulatory programs, the expansion of employee rights, state-owned industries, public education, and universal suffrage, were widespread and important). This failure, along with other developments such as the collapse of the USSR, indicated that scientific socialism was an imperfect guide to the future. By the end of the twentieth century, the term was mainly of historical interest.
See also: idealism; marxism; socialism
Engels, Frederick. (1880). Socialism: Utopian and Scientific. <http://csf.colorado.edu/psn/marx/Archive/1880-SUS>.