In theory, a patent confers perfect appropriability by granting legal monopoly of an invention for a limited period of time in return for a public disclosure that assures, again in theory, widespread diffusion of social benefits after the patent's expiration. The rationale for this social contract rests on the recognition that technological knowledge has certain attributes of a public good. From this perspective, knowledge, once created, is believed to be freely appropriable by others, and the free-rider problem thus limits the incentive to create new knowledge. By conferring property rights that restrict temporarily the wide use of new knowledge, the patent system is supposed to create the incentive to engage in inventive activity and to undertake the costly investment typically required to reduce an invention to practice.

Focusing on the Southern Bell Telephone Company, we propose a modified version of the predation hypothesis to explain Bell's "natural" monopoly over local telephone service. Southern Bell effectively eliminated competition through a strategy of pricing below cost in response to entry, which deprived competitors of the cash flow required for expansion even if it failed to induce exit; investing in toll lines ahead of demand, isolating independent companies in smaller towns and rural areas, and forcing them to consolidate on favorable terms; and influencing local regulatory policy in large cities to weaken rivals and ultimately to institutionalize the Bell monopoly.

Focusing on the Southern Bell Telephone Company, we propose a modified version of the predation hypothesis to explain Bell's "natural" monopoly over local telephone service. Southern Bell effectively eliminated competition through a strategy of pricing below cost in response to entry, which deprived competitors of the cash flow required for expansion even if it failed to induce exit; investing in toll lines ahead of demand, isolating independent companies in smaller towns and rural areas, and forcing them to consolidate on favorable terms; and influencing local regulatory policy in large cities to weaken rivals and ultimately to institutionalize the Bell monopoly.

In nursing this essay through several drafts, I have benefited greatly from suggestions by Edward Denison, Robert Evenson, Zvi Griliches, Richard Levin, John Kendrick, Edwin Mansfield, and Richard Murnane. Moses Abramovitz has been a source ofencouragement and good, substantive editorial advice, for which I am most grateful. The heterodox views are my own, although I share many of them with Sidney Winter.