Both of them also realized the necessity of fighting poverty and economic want and did not believe that the mythical 'invisible hand' of the free market economy would do so on its own. They were also common critics of at least some of the aspects of 'Classical Economics' such as the Say's Law. There, perhaps, the similarity between the two ends.
Being a conscious opponent of Trotskyism, Keynes was by implication a strong opponent of Marxism as well. He differed with the fundamental Marxist concept that the recurring crises of 'boom and bust' in Capitalism were due to structural contradictions in the Capitalist system arising from private ownership and production for profit. (Beams, para 3) He believed that such crises in Capitalism could be resolved by adopting the right economic policies within the system. In fact, Keynes was greatly concerned by the danger posed by Marxism to the Capitalist system during the prolonged failure of capitalist economies during the depression era. This is evident in a letter written by him to the incoming U.S. President Roosevelt in which he has expressed his apprehension that if FDR failed to correct the 'evils' in the economic system, revolution could occur. (Ibid) Keynes makes it clear in his "Essays in Persuasion" (published in November 1931) that the problem of "want and poverty" and "the economic struggle between classes and nations" was a transitory and unnecessary phenomenon that could be easily solved as the Western World had the "resources and techniques" to solve the problem. (Quoted by Beams)
The main difference between Marx and Keynes as economists was that Keynes believed in the Capitalist economic system and wanted to only change some of its existing 'evil' practices by some 'enlightened' policies. Unlike Marx, Keynes did not regard capitalism as doomed but was only interested in greater government intervention. He regarded government spending as 'priming the pump', which was no doubt an important departure from the existing laissez-faire understanding of economics at the time, but was by no means as revolutionary an idea as that of Marx expressed more than 70 years before Keynes presented his main economic thesis in "General Theory..." published in 1936. In the ultimate analysis, Keynes' objective was to achieve a 'controlled market economy' rather than a 'planned' one. Marx, on the other hand, was a revolutionary who believed that the Capitalist economic system was itself the 'root of all evil' and needed to be replaced completely.
Some of the similarities and differences in the economic philosophies of Marx and Keynes may be understood better if we consider the major philosophical influences on the two. Marx was greatly influenced by the German philosophers Friedrich Hegel and Ludwig Feuerbach. While Hegel is known for his philosophy of dialectical historicism, Feuerbach emphasized materialism. Combining the two philosophies Marx develop his own 'Materialist' concept of history. The major philosophical influences for Keynes were the analytical philosophy of G.E. Moore, and the pragmatic conservatism of Edmund Burke -- elements that are reflected in his economic theories. (Hall and Smith 245)
Marx and Keynes are without doubt, two of the most influential economists of the modern era. Marxism may have lost some of its luster in the wake of the Soviet Union's collapse but Marx's philosophy and economic theories about Capitalism cannot be ignored even if we do not agree with some of his radical conclusions. Keynesian Economics too seems to have fallen out of favor in the present-day emphasis on laissez faire and free markets; periodic economic crises around the world, though, continue to remind us about the validity of Keynes theory regarding the key role of governments in guiding the economic policies.
Beams, Nick. "A question on Marx and Keynes." World Socialist Web Site. August 8, 2001. May 9, 2005. http://www.wsws.org/articles/2001/aug2001/keyn-a08.shtml
Cline, Austin. "Karl Marx's Economic Theories." The Economics of Society and Religion. N.d. May 9, 2005. http://atheism.about.com/od/philosophyofreligion/a/marx_3.htm
Hall, John a. And Michael R. Smith. "The Political Consequences of Mr. Keynes." Canadian Journal of Sociology. 27.2 (2002): 245 +.
Kroessin, Ralf. "Economic Thought and the Role of the State in Late Development." Totse.com. 1998. May 9, 2005. http://www.totse.com/en/politics/economic_documents/167748.html
Marx, Karl. Capital, the Communist Manifesto and Other Writings. Ed. Max Eastman. New York: The Modern Library, 1959.
Marx was not just a theorist but also a revolutionary; and stated in his "Thesis on Feuerbach": "The philosophers have only interpreted the world, in various ways; the point, however, is to change it."
The Bolshevik Revolution in Russia (1917) and the Communist Revolution in China (1949) affected the lives of a significant percentage of the world population. Almost one-fourth of the world's population lived under governments that claimed to be Marxist in the second half of the 20th century.
Adam Smith had specified four stages of successive social development, i.e., the age of hunters, the age of herders or shepherds, the age of farmers and the commercial age
Capitalism, according to the Marxist definition, is a system in which the producers are the employees and do not have the means to own the equipment and material needed to produce the commodities.
Marx wrote in the "Communist Manifesto" that "The executive of the modern state is but a committee for managing the common affairs of the bourgeoisie."
Jean Baptiste Say (1767-1832), a French economist, was one of Adam Smith's most faithful disciples, who was a great believer in 'laissez faire' and the 'self-correcting' mechanism of a market economy.
In his work, "The Essence of Christianity," Feuerbach argued that God is really a creation of man and that the qualities people attribute to God are really qualities of humanity.