Eduard Bernstein (1850 - 1932) was a German social democratic Marxist theorist and politician. A member of the Social Democratic Party of Germany (SPD), Bernstein had held close association to Karl Marx and Friedrich Engels, but he began to identify what he believed to be errors in Marxist thinking and began to criticize views held by Marxism when he investigated and challenged the Marxist materialist theory of history. He rejected significant parts of Marxist theory that were based upon Hegelian metaphysics and rejected the Hegelian perspective of an immanent economic necessity to socialism.