The question this week is how Marxism came to be the dominant theoretical apparatus of socialist thinking from the late 19th century onwards. Indeed, despite being constantly pronounced dead, it still manages to maintain itself in political, theoretical and academic debate in much of the world. It could be argued that whereas Marx himself said that all criticism starts with a critique of religion, all criticism today has to start with a critique of Marx.
As arrogant and dogmatic as it sometimes sounds to our ears now, Marx's USP was that his and Engels' approach to understanding history was the first to be based on truly scientific socioeconomic analysis. With a nod towards Darwin, Marx and Engels contended that their analysis of history was akin to a theory of evolution based on the concrete evidence of material facts. They argued that the theories of their rivals, the utopian communists and anarchists as well as the Hegelians and liberals, were based in idealist moral abstractions which dealt in notions of freedom, justice, fairness and equality in what they called the political superstructure of society, while theirs were based on an objective and scientific understanding of the real but largely invisible forces at work in the socioeconomic base.
Marx and Engels saw change and revolution as historical necessities emerging out of material contingent reality driven by socioeconomic forces. They saw their task as unmasking those forces, subjecting them to radical critique and proposing a possible way forward. Everyone else, they thought, was essentially carrying on in the idealist tradition, which saw the motivating force behind history as the unfolding of abstract human freedom as an idea, will or imagination.
For Hegel history was the Absolute Spirit moving towards absolute self-consciousness through a process which moved from the way things were, via rising conflict and tension, to a newer, "higher" stage. This process of negation and the negation of the negation produced new outcomes and new forms of social organisation which would only come to an end when the final liberation of humanity was achieved.
http://www.guardian.co.uk/commentisfree/belief/2011/apr/11/marx-engels-science-marxism