By John A. Vasquez and Marie T. Henehan - Contributions by Stuart Bremer; Bruce Bueno de Mesquita; Paul F. Diehl; Joel King; Jacek Kugler; Russell J. Leng; Jack S. Levy; Manus I. Midlarsky; A F. K. Organski; Karen A. Rasler; Steve Rosen; J David Singer; R