The Rate of Time Preference and Dynamic Economic Analysis

Strong restrictions on the structure of preferences are a central feature in the received theory of intertemporal allocation. In fact, most of the modern literature concerned with capital-theoretic problems represents preferences by a functional in which an additive utility function is discounted by a constant rate of time preference. This specification is attractive because it is analytically tractable in dynamic models, and it clearly delineates how tastes and opportunities interact to determine an economy's (household's) paths of consumption and capital formation. However, its rigid structure (constancy of time preference) severely limits the conclusions and explanatory power of the corresponding models. This paper considers a class of utility functionals (in continuous time) which have the appealing feature that the rate of time preference depends systematically on an index of aggregate future consumption. The more flexible structure embodied in these functionals leads to important generalizations and modifications of standard conclusions. We highlight this added richness by examining five basic problems in dynamic economic analysis.