Eduard Bernstein in the context of "Democratic socialists"

Democratic socialism is a left-wing economic and political philosophy that supports political democracy and some form of a socially owned economy, with a particular emphasis on economic democracy, workplace democracy, and workers' self-management within a market socialist, decentralised planned, or democratic centrally planned socialist economy. Democratic socialists argue that capitalism is inherently incompatible with the values of freedom, equality, and solidarity and that these ideals can only be achieved through the realisation of a socialist society. Although most democratic socialists seek a gradual transition to socialism, democratic socialism can support revolutionary or reformist politics to establish socialism. Democratic socialism was popularised by socialists who opposed the backsliding towards a one-party state in the Soviet Union and other countries during the 20th century. In Scandinavian countries as well as others, people often use "social democracy" and "democratic socialism" interchangeably to describe leftist movements aiming for gradual, democratic reform.

The history of democratic socialism can be traced back to 19th-century socialist thinkers across Europe and the Chartist movement in Britain, which somewhat differed in their goals but shared a common demand for democratic decision-making and public ownership of the means of production and viewed these as fundamental characteristics of the society they advocated for. From the late 19th to the early 20th century, democratic socialism was heavily influenced by the gradualist form of socialism promoted by the British Fabian Society and Eduard Bernstein's evolutionary socialism in Germany.

Rosa Luxemburg (/ˈlʌksəmbɜːrɡ/ LUK-səm-burg; Polish: Róża Luksemburg [ˈruʐa ˈluksɛmburk] ; German: [ˈʁoːza ˈlʊksm̩bʊʁk] ; 5 March 1871 – 15 January 1919) was a Polish and naturalised-German Marxist theorist and revolutionary. She was a leading theorist of the Social Democratic Party of Germany (SPD) and later co-founded the anti-war Spartacus League, which evolved into the Communist Party of Germany (KPD). An influential member of the international socialist movement, she is remembered for her writings on imperialism and revolution, and as a champion of socialist democracy who famously stated, "Freedom is always and exclusively freedom for the one who thinks differently."

Born and raised in Russian-ruled Poland to a secular Jewish family, Luxemburg became active in revolutionary politics in her youth. She co-founded the Social Democracy of the Kingdom of Poland and Lithuania (SDKPiL), a party that rejected Polish nationalism in favour of an international class struggle. After moving to Germany in 1898, she became the foremost voice of the SPD's revolutionary wing. In her 1900 pamphlet Social Reform or Revolution?, she defended the necessity of revolution against the reformist theories of Eduard Bernstein, arguing that the struggle for reforms was a means to an end, not an end in itself. Inspired by the 1905 Russian Revolution, she developed a theory of the mass strike as the proletariat's most important revolutionary tool, emphasizing the spontaneous creativity of the working class.

Democratic socialism represents the modernist development of socialism and its outspoken support for democracy. The origins of democratic socialism can be traced back to 19th-century utopian socialist thinkers and the Chartist movement in Great Britain, which somewhat differed in their goals but shared a common demand of democratic decision making and public ownership of the means of production, and viewed these as fundamental characteristics of the society they advocated for. Democratic socialism was also heavily influenced by the gradualist form of socialism promoted by the British Fabian Society and Eduard Bernstein's evolutionary socialism.

In the 19th century, democratic socialism was repressed by many governments; countries such as Germany and Italy banned democratic socialist parties. With the expansion of liberal democracy and universal suffrage during the 20th century, democratic socialism became a mainstream movement which expanded across the world. Democratic socialists played a major role in liberal democracy, often forming governing parties or acting as the main opposition party (one major exception being the United States).

Social Reform or Revolution? (German: Sozialreform oder Revolution?) is an 1899 pamphlet by Polish-German Marxist theorist Rosa Luxemburg. Luxemburg argues that trade unions, reformist political parties and the expansion of social democracy—while important to the proletariat's development of class consciousness—cannot create a socialist society as Eduard Bernstein, among others, argued. Instead, she argues from a historical materialist perspective that capitalism is economically unsustainable and will eventually collapse and that a revolution is necessary to transform capitalism into socialism. The pamphlet was heavily influential in revolutionary socialist circles and along with Luxemburg's other work an important precursor to left communist theory.