In this paper, we prove in terms of the prototype model of social common capital that the optimum conditions for sustainable processes of capital accumulation involving both private capital and social common capital coincide precisely with those for market equilibrium with the social common capital taxes at certain specific rates under the stationary expectations hypothesis concerning the future schedule of marginal productivity of capital of all kinds.

We study how the use of judgment or “add-factors” in forecasting may disturb the set of equilibrium outcomes when agents learn by using recursive methods. We isolate conditions under which new phenomena, which we call exuberance equilibria, can exist in a standard self-referential environment. Local indeterminacy is not a requirement for existence. We construct a simple asset-pricing example and find that exuberance equilibria, when they exist, can be extremely volatile relative to fundamental equilibria.

Human capital is embodied in people of different generations whose lifetimes are finite. We show that the finiteness of people's lives precludes human capital accumulation from driving long-run aggregate economic growth unless sufficiently strong externalities from aggregate human capital are introduced. Two possible channels for carrying forward such externalities are (i) knowledge spillovers and (ii) public education spending. Our findings shed new light on the foundations of the Uzawa–Lucas growth model. We also show that the cross-sectional Mincer equation, generated by a linear human capital accumulation equation at the individual level, does not carry forward to aggregate data.

The aim of this paper is to examine whether the development of waste recycling activities can be a source of economic fluctuations. We assume that the recycling sector has four fundamental characteristics. (i) The production factors are restricted by the production of the last period. (ii) These production factors are waste for which the price determination is noncompetitive. (iii) The sector produces a recycled good, which is a perfect substitute for the primary good. (iv) It reduces the waste stream. We consider the simplest economy, with an infinitely lived agent and a life-cycle hypothesis for the goods. We show that the equilibrium is unique and is always determinate. In spite of the lack of indeterminacy, however, our economy can display cyclical behavior, depending on some usual conditions on parameters. Namely, the steady state may undergo a flip bifurcation or a Hopf bifurcation.

Since 1900, annual working hours per worker have been generally declining in the United States and in the main European economies. During this simultaneous decline the Europeans initially worked fewer hours than their American counterparts, worked more than the Americans starting in the early 1930s, and once again worked less than the American from the early 1970s on. Using a two-country model, this article argues that this dynamic pattern can be brought about by differences in the valuation of leisure by individuals in the compared economies.

Recently, several researchers have succeeded in producing expectation–driven cycles by balancing the tension between the wealth effect and the substitution effect stemming from the higher expected future productivity. Especially, seminal research by Christiano et al. (“Monetary Policy and Stock Market Boom–Bust Cycles,” mimeo, Northwestern University, 2007), explains “stock market boom–bust cycles,” characterized by increases in consumption, labor inputs, investment, and stock prices relating to high expected future technology levels. We, however, show that such expectation–driven cycles are difficult to generate based on “growth expectation,” which reflects expectations of higher productivity growth rates.

This paper examines optimal monetary policy under uncertainty about fundamental parameters of a dynamic stochastic general-equilibrium model. In contrast to previous studies, a microfoundation of the model leads this uncertainty to generate uncertainty not only about the transmission of monetary policy but also about the transmission of shocks and about a social welfare loss function. In the presence of such uncertainty, this paper finds conditions under which optimal discretionary policy responds to shocks more aggressively than in the absence of the uncertainty. These conditions depend crucially on the persistence of shocks and the magnitude of policy multipliers. To obtain the conditions, taking proper account of uncertainty about the transmission of shocks and about the welfare loss function is of crucial importance.

Empirical evidence shows that entrepreneurs hold a large fraction of wealth, have higher saving rates than workers, and face substantial uninsurable entrepreneurial and investment risks. This paper constructs a heterogeneous-agent general equilibrium model with uninsurable entrepreneurial risk and capital-market imperfections to explore the implications of uninsurable entrepreneurial risk for wealth distribution and aggregate activity in an incomplete market economy. It is shown that entrepreneurial risk can substantially affect both the wealth distribution and the macroeconomy.