This paper discusses that the main difference between social democracy and capitalism lies in the disagreement over human nature and economics. Social democracy is founded on the premise that a certain amount of competitiveness will allow the production of economic growth. This growth, in turn, stimulates the economy further. The competitiveness, meanwhile, derives naturally from the human trait of self-interest. Communism, however, holds that there is no such thing as human nature. Both Marx and Rousseau believed that man was social and that both could be reshaped. In other words, self-interest was socially constructed and man could be changed to reject his own interest. The difference between communism and social democracy, therefore, centres precisely on this disagreement over human nature. 10 pgs. 12 f/c. 9b.