THREE ESSAYS IN MACROECONOMIC THEORY: ENDOGENOUS CYCLES WITH UNCERTAIN LIFESPANS IN CONTINUOUS TIME. OVERLAPPING GENERATIONS, TRANSACTION COSTS AND THE TOBIN EFFECT. BUDGET DEFICITS IN A DYNAMIC DESCRIPTIVE MODEL

Endogenous Cycles With Uncertain Lifespans in Continuous Time. Endogenous equilibrium business cycles are found to result from heterogeneity and turnover of the labor force in a model where agents face a constant probability of death. Labor supply is endogenous, and retirement is modelled in continuous time as a constant decay of labor endowment. Hopt bifurcations are found to occur at interest rates above golden rule levels when the elasticities of substitution in utility and production are low. Attempts at intertemporal arbitrage by agents who live through the cycle are thwarted by the arrival of new entrants. Those who enter in boom times tend to be lower lifetime suppliers of labor than those who enter when human capital is low near the trough of the cycle.;Budget Deficits in a Dynamic Descriptive Model. Long run effects of deficit spending are examined in a dynamic, full employment, descriptive macro model with wealth effects. Ricardian equivalence is assumed not to hold. Investment takes place without adjustment costs. Given perfect foresight, the inflation rate is then simply the nominal interest rate less the marginal product of capital.;Multiple steady states occur under monetary financing of deficits, some of which are stable (implying non-uniqueness under perfect foresight). Saddlepath solutions occur under tax or bond financing. Crowding out takes place with tax financing and with stable cases of monetized deficits, but not with some saddlepath solutions under monetary or bond finance.;Overlapping Generations, Transaction Costs, and the Tobin Effect. Steady state welfare in an OLG model with transaction costs and capital is shown to be maximized at positive money growth, and in some cases, inflation. Increasing money growth moves the capital stock closer to the golden rule level, improving consumption possibilities. This effect outweighs the welfare losses from the distortionary inflation tax at low rates of money growth. The finding holds for linear or non-linear transaction costs occurring either in both periods of agents' lives or only in the second period. It also holds even when agents have fixed subjective discount factors.