People may be surprised to notice certain regularities that hold in existing knowledge they have had for some time. That is, they may learn without getting new factual information. We argue that this can be partly explained by computational complexity. We show that, given a knowledge base,...

We study transactions that require investments before trading in a competitive market, when forward contracts fixing the transaction price are absent. We show that, despite the market being perfectly competitive and subject to arbitrarily little uncertainty, the inability to jointly determine...

We examine the evolutionary foundations of intertemporal preferences. When all the risk affecting survival and reproduction is idiosyncratic, evolution selects for agents who maximize the discounted sum of expected utility, discounting at the sum of the population growth rate and the mortality...

Hierarchical organizations often perform poorly in inducing the adoption of innovations. The authors examine a principal offering contracts to agents who make unobservable effort and adoption-of-innovation choices (yielding moral hazard); who occupy jobs of differing, unobserved productivities...

We consider a market with "red" and "green" workers, where labels are payoff irrelevant. Workers may acquire skills. Skilled workers search for vacancies, while firms search for workers. A unique symmetric equilibrium exists in which color is irrelevant. There are also asymmetric equilibria in...