This is a really good paper on the contributions and thought of Milton Friedman.
At the beginning of his career, Friedman adopted two hypotheses that isolated him from the prevailing intellectual mainstream. First, central banks are responsible for inflation and deflation. Second, markets work efficiently to allocate resources and to maintain macroeconomic equilibrium. Because of his success in advancing these ideas in a way that shaped the understanding of the major economic events of this century and influenced public policy, Friedman stands out as one of the great intellectuals of the 20th century.