I wanna start with a simple thought experiment for the libertarians and classical liberals out there. Suppose that the harshest critics of the free market were right and you were wrong about the way in which free markets actually work. Suppose that free market really do lead the rich to get richer and the poor to get poorer. Suppose they lead the poor and working classes to live lifes of constant and increasing alienation in which they're continually subjected to exploitation and domination by those of greater economic power. If all this were true, would you still support the free market? If not, or if you had second thoughts, then I want to suggest, that this means you think that how the poor fair in the free markets is more than just an attractive selling point for free market views. It's a crucial element in the moral justification. And if you believe that, and I think many libertarians and classical liberals do, then perhaps you're not so far off from believing in an idea that most libertarians think they reject - the idea of social justice.

Matt Zwolinski "What's Right About Social Justice"