How Braess’ paradox solves Newcomb's problem*

Preliminary versions of this paper were read at the annual Dubrovnik Philosophy of Science Conference on 11 April 1992 and at the University of Victoria on 9 March 1993. Thanks go to members of both audiences, as well as to Adam Constabaris, Eric Borm, Colin Gartner, Joan Irvine, Kieren MacMillan, Steven Savitt and Jeff Tupper for their helpful comments. In addition, special thanks goes to Leslie Burkholder and Louis Marinoff whose many detailed suggestions and ideas were crucial in the writing of this paper.

Abstract

Newcomb's problem is regularly described as a problem arising from equally defensible yet contradictory models of rationality. Braess’ paradox is regularly described as nothing more than the existence of non‐intuitive (but ultimately non‐contradictory) equilibrium points within physical networks of various kinds. Yet it can be shown that Newcomb's problem is structurally identical to Braess’ paradox. Both are instances of a well‐known result in game theory, namely that equilibria of non‐cooperative games are generally Pareto‐inefficient. Newcomb's problem is simply a limiting case in which the number of players equals one. Braess’ paradox is another limiting case in which the ‘players’ need not be assumed to be discrete individuals. The result is that Newcomb's problem is no more difficult to solve than (the easy to solve) Braess’ paradox.

Notes

Preliminary versions of this paper were read at the annual Dubrovnik Philosophy of Science Conference on 11 April 1992 and at the University of Victoria on 9 March 1993. Thanks go to members of both audiences, as well as to Adam Constabaris, Eric Borm, Colin Gartner, Joan Irvine, Kieren MacMillan, Steven Savitt and Jeff Tupper for their helpful comments. In addition, special thanks goes to Leslie Burkholder and Louis Marinoff whose many detailed suggestions and ideas were crucial in the writing of this paper.