An unorthodox economist and philosopher whose criticism of Central Planning (both in terms of freedom and efficiency) was quite prophetic, at a time when most social scientists preached the 'convergence' of Capitalism and Communism. In other ways, Hayek's predictions were less accurate, notably his belief that increasing state interference would lead to Totalitarianism-this has never happened anywhere. Communist regimes have always come to power through force in transitional societies with weak states (failing monarchies and military dictators, usually) or expanded by military invasion. Hayek's conflating of social democracy with Totalitarianism is misleading at best, scare-mongering at worst. More seriously, Hayek dichotomy of state vs. individual is far too simplistic and fails to take into account other factors (corporate power, ethnic conflict, technology and demographics, to name a few). Hayek made a few notable contributions to economics and philosophy, but he does not rise above the (high) second rank in either field.

one of the top 10 all time philosophers

Hayek may well go down as the pivotal thinker of the 20th century: our equivalent to Aristotle or Plato. Along with his teacher, Ludwig von Mises, Hayek demonstrated the impossibility of economic calculation under socialism (i.e., in the absence of free markets). But the greatest of Hayek's insights were not specifically about economics. "The Road to Serfdom" was a warning to Western democracies that the socialists' road of good intentions would be a road to enslavement by centralized powers, as it had been in Hayek's native Austria, in Germany, in Russia, etc. That book woke up the classical liberal community and spurred them to greater action. Hayek was a strategic thinker about how to change the world of ideas (see his essay "Intellectuals & Socialism"). In 1947, he founded the Mont Pelerin Society to create an international network of people devoted to reclaiming liberty. Hayek, MPS, and the think tanks he inspired (via the legendary Antony Fisher) did much to make possible the revitalization of classical liberal ideas in the late 20th century (in the European sense of the word "liberal", which is opposite of its modern American meaning). The rise of Thatcher and Reagan -- and then the fall of communism worldwide -- would have been unthinkable without the groundwork he laid. As his rival/friend Keynes said, economists wield more power than are commonly understood... Thankfully, after a century of Marxism and then Keynesianism, more and more of the field have turned toward the ideas of the Austrian School, of which F.A. Hayek was its greatest member. I would give extra points to Hayek if I could because, by all accounts, he was also a warm human being, who always treated even his ideological enemies with great respect.