A nova teoria do comercio é na verdade uma coleção de modelos econômicos de comércio internacional que destaca o papel de retornos crescentes de escala e efeitos de rede, que foram desenvolvidos no final dos anos 70 e início dos anos 80 por economistas liderados por paul Krugman. Os novos teóricos do comércio trocaram a hipótese de retornos constantes para retornos crescentes de escala e mostraram que em alguns casos usar medidas protecionistas para ajudar na construção de uma base industrial pode ser uma medida benéfica para países em desenvolvimento. Raciocínios desse tipo são usados pelos teóricos do comércio desde os primeiros mercantilistas. A importância de se proteger “indústrias nascentes” foi defendido pelo menos desde o século XVI por John Carry, por mercantilistas franceses e italianos, entre outros. Alexander Hamilton propôs em 1791 que esta fosse a base para a política comercial dos EUA. O que era “novo” na nova teoria do comércio era o uso de economia matemática para modelar os retornos crescentes de escala e, especialmente, o uso de efeitos de rede para entender a dinâmica de comercio entre países. Os modelos desenvolvidos mostravam a tendência concentração industrial e concorrência monopolista ou até mesmo a situações de oligopólio em setores com retornos crescentes de escala.

Alguns economistas, como Ha-Joon Chang, argumentaram que as políticas protecionistas haviam facilitado o desenvolvimento da indústria automobilística japonesa na década de 1950, quando as cotas e os regulamentos impediam a concorrência das importações. As empresas japonesas foram incentivadas a importar tecnologia de produção estrangeira, mas foram obrigadas a produzir 90% das peças no mercado interno. Os consumidores japoneses sofreram no curto prazo por não conseguirem comprar veículos superiores produzidos pelo mercado mundial, mas acabaram ganhando por ter uma indústria local que superou seus rivais internacionais. A teoria foi inicialmente associada a Paul Krugman no final da década de 1970; Krugman afirma que ouviu sobre a concorrência monopolista de Robert Solow. Olhando para trás em 1996, Krugman escreveu que a economia internacional, uma geração antes, ignorou completamente os retornos de escala. “A ideia de que o comércio poderia refletir uma sobreposição de especializações de retornos crescentes em vantagem comparativa não existia”. Em 1976, no entanto, O economista Victor Norman elaborou os elementos centrais do que veio a ser conhecido como a teoria de Helpman-Krugman. Ele escreveu e mostrou para Avinash Dixit. No entanto, ambos concordaram que os resultados não eram muito significativos. De fato, Norman nunca escreveu o paper, muito menos tentou publicar. A participação formal de Norman na corrida vem dos capítulos finais do famoso livro Dixit-Norman. As novas teorias do comércio são freqüentemente baseadas em premissas como a concorrência monopolista, retornos crescentes de escala e economias de rede.

Por que a divergência de renda entre países pobres e ricos no mundo so aumenta?

A microeconomia da produtividade: economias de escala, grandes empresas e grandes países

entrevista de Paul Krugman sobre o tema: https://piie.com/experts/peterson-perspectives/trade-talks-episode-66-paul-krugman-talks-trade?fbclid=IwAR3KzR7fkonw4VoEL0268er3QcATGfw7PwTqzoshqLWqPGO5dsS5OXvj5-I

 Rodrik 1988 sobre a nova teoria do comercio:

“To many policymakers in developing countries, the “new” trade theory, with its emphasis on imperfect competition and returns to scale, must appear as a vindication of sorts. For the recent literature has led to a considerable weakening of the traditional neoclassical presumption against policy intervention in foreign trade. The journals are now filled with examples of governments “creating” comparative advantage by exploiting imperfections in markets for goods and technologies and increasing returns to scale. This new emphasis on the indeterminacy of comparative advantage contrasts starkly with the advice these policymakers have typically received regarding the necessity to specialize in unsophisticated, labor-intensive commodities. Indeed, by focusing on learning effects, the new literature has provided some of the best arguments for infant-industry protection since Alexander Hamilton and Friedrich List. The diehard import substituters may now legitimately wonder if the learning processes so important to the U.S. semiconductor industry (see Baldwin and Krugman 1986) are not equally relevant to a wide spectrum of basic industries in developing countries.

As the last example illustrates, the new literature is also a frustrating reminder to the South that too often ideas become intellectually respectable only when they become congruent with the interests of major Northern countries. Hence it is more than a little ironic that the new trade theory has developed against the backdrop of trade conflicts among developed countries, and between the United States and Japan, in particular. Market imperfections of the sort analyzed in this context would appear to be, if anything, more serious in the developing countries. Yet the new insights have still to penetrate the vast literature on trade policy in developing countries. Anne Krueger’s (1984) survey of the field, for example, found no applications to developing countries worthy of mention. The predominant approach to trade policy in developing countries remains based on intuition and insights deriving exclusively from models with perfect competition. In practice, of course, the actual policy debates between import substituters and liberalizers have long been carried outside the confining framework of perfect competition. The import substituters remain suspicious of trade liberalization for reasons, not always well articulated, having to do with technological externalities and scale effects.

They fear that resources will be reallocated away from the more modern, capital- and knowledge-intensive sectors with unexploited scale economies. The liberalizers, on the other hand, have long proceeded in syncretic fashion. In their role as academic economists, they typically build models in which perfectly competitive markets guide the allocation of resources along lines of comparative advantage. But in their role as policy advocates, they have been driven by the discouragingly small size of the Harberger triangles their models yield to fortify their arguments by appeal to the procompetitive and beneficial scale effects of more open trade regimes. Hence the great advantage of the new approach: it may bring theory and policy much closer than they have so far stood. In truth, there are elements in the new theories of trade that give comfort to both camps.

In the presence of imperfect competition and increasing returns to scale, trade liberalization is compatible both with a magnification of the welfare gains and with welfare losses. It all depends on how the economy is expected to adjust, which in turn depends on the frustrating ambiguities of oligopoly theory. At one extreme, we could imagine that free entry eliminates all excess profits and that liberalization rationalizes industry structure by reducing the number of firms and forcing the remaining ones down their average cost curves. In such a view of the world, the benefits of trade liberalization can easily amount to several times the usual Harberger triangles. Harris’s (1984) calculations with such a model of Canada show that industry rationalization reduces manufacturing costs to such an extent that the net outcome is an expansion of the manufacturing sector, a sector in which Canada has prima facie a “comparative disadvantage.” This kind of story suggests a wonderful way to sell trade liberalization to policymakers in developing countries: liberalization may actually help expand the modern sectors! But at the other extreme, we can imagine a world in which the contracting sectors tend to be those with Imperfect Competition in Developing Countries with supernormal profits and unexploited industrywide scale economies. The protectionists’ fears may then well be justified.”

paper Rodrik (1988), discurso de Krugman para Nobel