The possibility, nature and evolution of capitalism have been a major concern for philosophers and political scientists since the very earliest periods of the emergence of markets. In historical retrospect an oscillation between two visions can be observed. For classical and, more recently, neoclassical economists, the market mechanism is basically self-equilibrating, the only source of crises being clumsy interventions on the part of political authorities or the legacy of inadequate and obsolete social relations. But first Marxists and then Keynesians have repeatedly argued the very opposite — that the pure market mechanism may lead to major crises, financial disequilibria, rising inequalities or stagnation and long run unemployment. Therefore state intervention in relation to the nationalization or socialization of investment decisions may help to maintain the viability of a mature capitalist system. This long swing in ideas about the role of the market has been clearly pointed out by Karl Polanyi (1944; 1983).