Additive and Multiplicative Uncertainty Revisited: What Explains the Contrasting Biases?

above the certainty level while for additive uncertainty the price should be lower than the certainty level. This note gives an intuitive explanation for the result after first presenting a parsimonious review of the two models. We also discuss which, if either, of the two models is more realistic. Received December 14, 2001; revised version received July 16, 2002 Published online: April 30, 2003 We thank referees for helpful comments. Ciaran Driver would like to acknowledge the research facilities from ANU, Canberra for their help in writing this paper.     

Ill-behaviour of transformation-frontiers with environmental quality versus pollution

If one looks at environmental quality N as a renewable natural resource (with its own natural dynamics) which is changed by emissions Z, then one gets a better understanding of the shape of the damage function. In the case of a logistic growth dynamics one obtains a well-shaped transformation frontier N(Z), even in a two-species natural dynamics. For a more general natural interaction in the framework of a prey-predator model one obtains the possibilities of a cusp catastrophe which makes the transformation frontier N(Z) ill-shaped for the standard arguments of economists and their most favoured environmental policy instruments.     

Intertemporal Equity and Hartwick's Rule in an Exhaustible Resource Model*

In a standard exhaustible resource model, it is known that if, along a competitive path, investment in the augmentable capital good equals the rents on the exhaustible resource (known as Hartwick's rule), then the path is equitable in the sense that the consumption level is constant over time. In this paper, we show the converse of this result: if a competitive path is equitable, then it must satisfy Hartwick's rule.