Political Competition: Theory and Applications. By John E. Roemer. Cambridge, MA: Harvard University Press, 2001. 352p. $60.00.

John Roemer sets out to slaughter a golden calf of positive political theory: the Downsian model of electoral competition and its famous implication, the median voter theorem. Roemer contends that not only is the premise of the Downsian model—political parties seeking election without policy objectives of their own—historically incorrect, but it also leads to implausible predictions. Throughout political history, he postulates, parties have represented disparate interests and have advocated divergent policies; thus, a model that is premised on the opposite and predicts convergence as the only equilibrium—provided an equilibrium even exists—cannot be the right tool for analyzing politics.