Part I of this chapter includes the debate between Paul Samuelson and Milton Friedman, which Keynes and Hayek had started. Friedman and Samuelson deepened and extended it. Both were initially inspired by the Keynesian Revolution. Later, Friedman distanced himself from Keynes. During the 1970s, Keynesianism was eclipsed by neoclassical economics, in which Friedman played a prominent part. Like Hayek, he influenced economic policymaking in America, Great Britain, and other countries, such as Chile, which became known as neoliberalism. Part II —describes why Samuelson remained, in philosophical terms, a liberal, while Friedman gradually flirted with libertarianism, without becoming one. Robert Nozick’s philosophy of libertarianism is summarized at the end of the chapter.