Vladimir Lenin
In 1903, Lenin had a major argument with another leader of the party, Julius Martov, which divided the party in two. Lenin wanted to establish socialism right away, rather than establishing capitalism first and then making the transition to socialism. Martov disagreed, he wanted to cling to the Classical Marxist idea that in order to achieve socialism, you must go through capitalism first. People who agreed with Martov were called Mensheviks (meaning "the minority"). The people who agreed with Lenin were called Bolsheviks ("the majority").