Nash equilibrium under knightian uncertainty: breaking down backward induction (extensively revised version)

We define Nash equilibrium for two-person normal form games in the presence of uncertainty, in the sense of Knight(1921). We use the fonna1iution of uncertainty due to Schmeidler and Gilboa. We show tbat there exist Nash equilibria for any degree of uncertainty, as measured by the uncertainty aversion (Dow anel Wer1ang(l992a». We show by example tbat prudent behaviour (maxmin) can be obtained as an outcome even when it is not rationaliuble in the usual sense. Next, we break down backward industion in the twice repeated prisoner's dilemma. We link these results with those on cooperation in the finitely repeated prisoner's dilemma obtained by Kreps-Milgrom-Roberts-Wdson(1982), and withthe 1iterature on epistemological conditions underlying Nash equilibrium. The knowledge notion implicit in this mode1 of equilibrium does not display logical omniscience.

Nash equilibrium under knightian uncertainty: breaking-down backward induction

We present two alternative definitions of Nash equilibrium for two person games in the presence af uncertainty, in the sense of Knight. We use the formalization of uncertainty due to Schmeidler and Gilboa. We show that, with one of the definitions, prudent behaviour (maxmin) can be obtained as an outcome even when it is not rationalizable in the usual sense. Most striking is that with the Same definition we break down backward induction in the twice repeated prisoner's dilemma. We also link these results with the Kreps-Milgrom-Roberts-Wilson explanation of cooperation in the finitely repeated prisoner's dilemma.

A note on growth and inflation

A simple exercise on growth and inflationary financing of public expenditures is presented in this note. In a parameterized overlapping generations mode1 where government expenses positivc1y affects the growth rate of human capital, steady state capital and output increase with inflation, reproducing the so called Tobin effect. For large inflation rates, however, government authorities cannot affect real variables and there are only nominal effects. It is also shown that the optimal policy implies some inflation but not growth maximization.

Aplicabilidade de teorias: microeconomia e estratégia empresarial

A matemática é um bem de capital, lógico e geral, para a construção da ciência empírica. A ciência empírica abstrata, aqui representada pela microeconomia, é um bem de capital, lógico, mas especifico, para a construção da ciência aplicada. A ciência aplicada, aqui representada pela teoria positiva da estratégia empresarial, é um bem de capital, dialético e específico, para o aperfeiçoamento da arte da ciência, isto é, do domínio da realidade. A complementariedade entre estas esferas do saber é obvia, mas encontra-se ofuscada pelo Vício Ricardiano de muitos economistas. Sob esta visão, faço um estudo de caso do trabalho de H. Igor Ansoff, precursor da teoria de estratégia empresarial. Partindo da iluminação neoclássica, Ansoff constatou penosamente a insuficiência dela. A prática empresarial exigia também iluminações que só a politica, a sociologia, e a psicologia podiam proporcionar. Através do entrelaçamento dialético ou quase-lógico delas, a teoria estratégica constituiu-se na indispensável passagem para a prática. A teoria aplicada da passagem para a prática da política econômica não é ensinada hoje. A lacuna é sugerida pelo estudo, transparecendo a maior causa para o desprestígio atual do economista, no Brasil e no Mundo.

Endogenous time-dependent rules and inflation inertia: preliminary version

When policy rules are changed, the effect of nominal rigidities should be modelled through endogenous pricing rules. We endogenize Taylor (1979) type pricing rule to examine the output effects of monetary disinflations. We derive optimal fixed-price time-dependent rules in inflationary steady states and during disinflations. We also develop a methodology to aggregate individual pricing rules which vary through disinflation. This allows us to reevaluate the output costs of monetary disinflation, including aspects as the role of the initial leveI of inflation and the importance of the degree of credibility of the policy change.