If Keynes was the most influential economist of the first half of the 20th century, Friedman was the most influential of the second half. Republican Richard Nixon once pointed out that "we are all Keynesians now." Equally, any honest Democrat will admit that we are all Friedmanites now. We are because he won so many of his arguments with the conventional wisdoms of his time. The ideas that inflation does not buy more prosperity, that the draft could be replaced with the volunteer army and that giving more choice to parents improves schools are just a few of Friedman's heresies that are today's orthodoxy.
Summers is a Harvard economist and was Treasury Secretary under President Clinton