Fedor Dan was born in St. Petersburg, Russia, in 1871. As a young man he joined the Union of Struggle for the Emancipation of the Working Class. Arrested in August, 1896, Dan was exiled to Orlov for three years.
On his return he joined the Social Democratic Labour Party (SDLP) and attended the Second Congress of the Social Democratic Labour Party in London in 1903. At the Congress there was a dispute between Vladimir Lenin and Julius Martov, two of SDLP's leaders. Lenin argued for a small party of professional revolutionaries with a large fringe of non-party sympathizers and supporters. Martov disagreed believing it was better to have a large party of activists.
Julius Martov based his ideas on the socialist parties that existed in other European countries such as the British Labour Party. Lenin argued that the situation was different in Russia as it was illegal to form socialist political parties under the Tsar's autocratic government. At the end of the debate Martov won the vote 28-23 . Vladimir Lenin was unwilling to accept the result and formed a faction known as the Bolsheviks. Those who remained loyal to Martov became known as Mensheviks.
Dan supported Julius Martov and along with Pavel Axelrod, Leon Trotsky, Irakli Tsereteli, Moisei Uritsky, and Noi Zhordania, became a Menshevik. He also joined the editorial board of its journal, Iskra and co-editor with Martov of Voice of the Social Democrat.
After several years in exile Dan returned to Russia in January, 1913. He lived in St. Petersburg where he edited a variety of newspapers published by the Mensheviks.
On the outbreak of the First World War, Dan was arrested and then exiled to Minusinsk. He was released in 1915 when he agreed to serve in the Russian Army as a surgeon.
Dan returned to the capital after the February Revolution and along with Irakli Tsereteli, argued that the Mensheviks should join the the Provisional Government. He also upset the Bolsheviks by fully supporting the war effort against the Central Powers.
After the October Revolution, Dan was a strong opponent of the Bolsheviks. For a while he was a member of the small Menshevik opposition group in the Constituent Assembly but in 1918 it was banned along with other political parties by the Soviet government. Dan continued to denounce the persecution of liberal newspapers, the nobility, the Cadets and the Socialist Revolutionaries and after being arrested in 1921 he was sent into exile.
When the Soviet Union was attacked by Germany in June, 1941, Dan gave his full support to his former country. This was reflected in his book, the Origins of Bolshevism (1943), where he argued that Bolshevism had been chosen by history to be "the carrier of socialism, the key idea of our epoch". However, he continued to argue for the humanization and democratization of the Soviet government.
Fedor Dan died in 1947.