You might want to read this linked article from Monthly Review magazine on Piketty’s Capital. Here are a couple of excerpts:
To understand the nature of this crisis of received economics it is necessary to look at the two principal bulwarks of neoclassical theory, which were originally erected in response to socialist critics. The first is the notion that a freely competitive capitalist economy left to itself generates full employment, indicating that unemployment is the product of various frictions, imperfections, or government interference. The second is the related proposition that income and wealth inequality are determined by the “marginal productivity” (or relative contributions to output) of the various factors of production, chiefly capital and labor—a logic that is extended to the contributions of individuals themselves.
Writing for the Wall Street Journal, Peter Thiel, co-founder of PayPal, declared that “Capitalism is premised on the accumulation of capital, but under perfect competition, all profits get competed away…. Only one thing can allow a business to transcend the daily brute struggle for survival: monopoly profits…. Monopoly is the condition for every successful business.” Indeed, this might even stand as the credo of today’s generalized monopoly capital.