In the (1955) edition of his top-selling Economics text, Paul Samuelson claimed economists had finally determined how economies worked. As he put it:
In recent years 90 percent of American economists have stopped being “Keynesian economists” or “anti-Keynesian economists.” Instead they have worked towards a synthesis of whatever is valuable in older economics and in modern theories of income determination. The result might be called neo-classical synthesis and is accepted in its broad outlines by all but about 5 percent of extreme left wing and right wing writers.