Dr. Thomsas Sowell says he was a Marxist in his formative 20s. After working as a summer intern for the federal government in Puerto Rico working on minimum wage laws, he became a free market economist.

Milton Friedman was his mentor and advisory when he was a student at the University of Chicago. He doesn't like labels regarding whether he is a conservative, libertarian or such. He says he's more of a conservative with libertarian leanings.

His book A Conflict of Visions: Ideological Origins of Political Struggles is an excellent read. It talks about the difference between conservatives and liberals.