"Free markets" is a very general term. There are all sorts of problems that will emerge. Free markets work best when the transaction between two individuals affects only those individuals. Most often, a transaction between you and me affects a third party. That is the source of all problems for government. That is the source of all pollution problems, of the inequality problem. This reality ensures that the end of history will never come.
Milton Friedman. . . it is worth discussing radical changes, not in the expectation that they will be adopted promptly but for two other reasons. One is to construct an ideal goal, so that incremental changes can be judged by whether they move the institutional structure toward or away from that ideal. The other reason is very different. It is so that if a crisis requiring or facilitating radical change does arise, alternatives will be available that have been carefully developed and fully explored.
Milton FriedmanThe argument for the free market is a complicated and sophisticated one and depends on demonstration of secondary effects. I have confidence market efficiency will win out.
Milton Friedman