states that the price for a good is set by the amount of socially acceptable labour that goes into production. In Dobb's Theories of Value and Distribution Since Adam Smith: Ideology and Economic Theory, he argued that marginal utility and individual satisfaction cannot determine prices, as marginalism suggests. He saw a person's preferences and level of satisfaction as heavily dependent on individual wealth, so that marginal utility is determined by spending power. This, according to Dobb, was the distribution of wealth that could alone change prices, as price depended on how much someone would spend. So he argued that individual behaviour cannot influence prices, as there are many other factors such as labour and spending power to affect them. Dobb dismissed the market-socialist model of Oskar Lange and contributions of "neo-classical" socialists as illegitimate "narrowing of the focus of study to problems of exchange-relations." Many of Dobb's works have appeared in other languages. His short Introduction to Economics was translated into Spanish by the Mexican intellectual Antonio Castro Leal for the leading Mexican publisher Fondo de Cultura Economica, and has gone through more than ten editions since 1938. For Dobb, the central economic challenges for socialism relate to production and investment in their dynamic aspects. He identified three major advantages of planned economies: antecedent co-ordination, external effects and variables in planning. Antecedent co-ordination Planned economies employ antecedent co-ordination of the economy, whereas a market economy atomises its agents by definition and the expectations that form the basis of their decisions are always based on uncertainty. There is a poverty of information that often leads to disequilibrium and can only be corrected in a market ex post (after the event), so that resources are wasted. An advantage of antecedent planning is removal of marked degrees of uncertainty in a context of coordinated and unified information-gathering and decision-making prior to the commitment of resources. External effects Dobb was an early theorist to recognise the relevance of external effects to market exchanges. In a market economy, each economic agent in an exchange makes decisions based on a narrow range of information in ignorance of wider social effects of production and consumption. When external effects are significant, this invalidates the information transmitting qualities of market prices, so that prices do not reflect true social-opportunity costs. Dobbs claimed that contrary to the convenient assumptions of mainstream economists, significant external effects are in fact pervasive in