Bump for Milton Friedman, greatest economist of the 20th century.
Best economist of the 20th century? Bullcrap.. (Norvokov)
Probably a better, or at least equal choice would be Freidrich Hayek, author of The Road to Serfdom
I'll copy that main quote from the web page:
A claim for equality of material position can be met only by a government with totalitarian powers
Adam Smith was the greatest economist of his time, but not for today.