Two fields of thought evolved simultaneously, but scholars in one ignored the evolution of the other. The first was the theory of monopoly, whose broad nineteenth-century definition narrowed considerably during the twentieth century. Concepts contained in its original incarnation attained...

The prevailing paradigm of medieval industry rests on the belief that guilds monopolized markets for manufactures. The type of market power possessed by guild which manufactured durable goods is, however, unclear. Scholars have shown manufacturing guilds did not possess natural monopolies.