Elasticidade de expectativas e surpresa potencial: reflexões sobre a natureza e a estabilidade do equilíbrio sob incerteza

Na liteptura economica, ja se tornou lugar-commn apontar a incompatibilidade entre as nocoes de incerteza e equilibrio. Esta incompatibilidade e argmnentada, algmnas vezes, em termos de transitoriedade de estados enraizada na volatilidade causada pela incerteza, tornando inutil, ao menos empiricamente, o estudo de estados de equilibrio. Este argumento, conquanto verdadeiro em seus termos, e, teoricamente, irrelevante. Com mais rigor, porem, aponta-se tambem a incompatibilidade entre o suposto da incerteza reinante em economias de mercado e os requerimentos informacionais da detenninacao do equilibrio. Nesta linha, argmnentou Shaclde: "( ... ) the equilibrium thought-scheme or conceptual arrangement makes it logically possible to suppose that each person knows everything about the circumstances of his act that bears upon its outcome and ought, therefore, to bear upon his choice of it; and in cases where a solution exists, it makes each person 's act fully explainable as the response which, ali relevant circumstances being known to him, he is logically bound to make to these circumstances if his desires are to be as fully satisfied as these circumstances allow. ( ... ) The vehicle of infonnation, the means by which this economic-equilibrium model solves the problem of how the necessafY knowledge for rational action can be supposed to be available to each member of the society, is market price, which, by the meaning we give to the word 'market' , is declaratory, public and unifonn. ( ... ) In the equilibrimn model there is no futufe, for the future essentially implies ignorance" (Shaclde, 1965, p. 13, 17,23). A ideia de equilibrio que esta sendo discutida por Shaclde e, naturalmente, a adotada pela teoria ortodoxa segundo a qual se esta em um estado de equilibrio: "When all the 'individuais' in it are choosing those quantities,