Non-competing factor groups and the normative propositions of trade theory

The Walras-Arrow-Debreu-McKenzie model of general equilibrium forms the basis of almost all normative trade theory. In that model, a factor of production might be completely or incompletely immobile between alternative occupations. Whether it ever abandons an initial occupation depends on the cost of moving to each of the alternative occupations. It is not to be expected that, in equilibrium, a factor will receive the same reward in each occupation; non-competitive factor groups will be the rule. It is puzzling then that, in recent years, normative trade theory has developed in complete denial of non-competing groups. It is here shown that the occupational immobility of factors does not endanger any of the well-known normative propositions of the theory of international trade.