This paper is concerned with situations where firms not only recognize the dependence of quality on price (of productivity on wages, of default probability on the interest rate charged), but also attempt to use what control they have over price (wages, interest rates) to increase their profits. The recognition of this possibility has important implications for economic theory, which have recently been explored in a large number of papers in several disparate fields. The objective of this paper is to survey these papers and to draw out the central themes of this literature. This paper is divided into four parts, In Part I, we discuss the most important implications of the dependence of quality on price for competitive equilibrium theory--the repeal of the law of supply and demand (Part I.1), the repeal of the law of the single price (Part I.2), the existence of discriminatory equilibria (Part I.3), the comparative static consequences (Part I.4), and the inefficiency of market equilibria (Part I.5). Part II discusses alternative explanations for the dependence of quality on price in labor, capital, and product markets.

This paper establishes that when there is not a complete set of markets but more than one commodity the stock market equilibrium will not in general be a constrained Pareto optimum. The economy will lack both the property of exchange and production efficiency. Necessary conditions which must be satisfied if the economy is to be a constrained Pareto optimum for all technologies are derived; if all individuals have identical, homothetic indifference maps, then either there must be unitary price elasticities (so there is no effective risk) or all individuals must have the same degree of risk aversion (so there is no trade on the stock market).