I define market fundamentalism as the undue extension of market values to other spheres of social life, notably politics. Economic theory claims that in conditions of general equilibrium, the invisible hand assures the optimum allocation of resources. This means that people pursuing their self-interest are indirectly also serving the public interest. It gives self-interest and the profit motive a moral imprimatur which allows them to replace virtues like honesty, integrity, and concern for others. The argument is invalid on several counts. First, financial markets do not tend toward equilibrium. General equilibrium theory reached its conclusions by taking the conditions of supply and demand as independently given. The invisible hand of the market then brings supply and demand into equilibrium. This approach ignores the reflexive feedback loops between market prices and the underlying conditions of supply and demand. It also ignores the visible hand of the political process which lies hidden behind the market mechanism. Second, general equilibrium theory takes the initial allocation of resources as given. This rules out any consideration of social justice. Most importantly, the theory assumes that people know what their self-interest is and how best to pursue it. In reality, there is a significant gap between what people think and what the facts are. Nevertheless, market fundamentalism has emerged triumphant. How could that happen?