Marx economics theory

Question

Before Marx, economic theory had two big names: Adam Smith and Ricardo. It is well known that Marx used their work. When at school I was told without much specific that Marx had substantial contribution. What is the most important contribution of Marx to the theory of economics?

PS. Some people claim that the so-called surplus value was introduced by Marx and is his major contribution. But according to this Wikipedia article this concept existed and was studied by both Smith and Ricardo. So my question remains.

Note that Marx created "Political Economy", but that is not an economics theory.

Answer 1

Since there is no good answer, I will post my thoughts. First, background. As many people in Soviet Union, I studied various parts of Marxism for many (more than 10) years. I was a good student, A's in all subjects, and unlike many, I actually read what the man wrote. So I believe that I know Marxism at least as well as a Professor of Marxism in a major US University (lots of them do not know even the "Gotha Program" or "Marx's letter to J. Weydemeyer in New York" , where he introduced the concept of "Proletarian Dictatorship". None of the Professors I spoke with could formulate the 11-th thesis of Feuerbach: "Philosophers have hitherto only interpreted the world in various ways; the point is to change it".

So to my answer. There is no other scientist in the World, past of present, who has been so politicised -- for obvious reasons. Marx created (basically singlehandedly) Political Science, the theory of class struggle for power. For this he used many classical parts of science: Economy, Philosophy, etc. He did not contribute much to these parts, but he showed how they can be used and interpreted in terms of political science. In particular, in terms of Economics theory, which basically dealt, as described by the famous African-Russian writer Pushkin, with questions like "как государство богатеет и чем живёт, и почему не нужно золота ему, когда простой продукт имеет" (a very rough translation: "how the state gets richer and how it lives, and why it doesn't need gold when it has a simple product"), Marx did not contribute much over Smith and Ricardo. But he found a strong (for him and his followers at least) connection between the Economics theory and Political Economy. Similar - in Philosophy. He did not overdo Hegel or even Feuerbach. But he created "Dialectical materialism.

Answer 2

The concept of "surplus value" existed before Marx, but he developed a comprehensive theory, trying to prove it by statistical data. His theory predicted that development of capitalism will lead to increasing exploitation, impoverishment of the mass of proletarians, and this must inevitably lead to a "proletarian revolution". History showed that this never happened. (Bolsheviks who seized power in Russia in 1917 claimed that this was a "proletarian revolution" but it was not. Similar claims were made by other communist parties who tried to seize power). By the early 20th century it became clear to many followers of Marx that the main conclusion of Marx's theory was wrong, and "marxism" was reformed giving rise to modern socialist parties which come to power by democratic means in many countries of Europe. But they are not talking about "proletarian revolution" anymore. Still they maintain that many features of Marx's criticism of capitalism remain valid, but that the transition to socialism will happen in a peaceful, democratic and gradual way.