> having two competitors is what causes the most bloodshed in the world
If by "most bloodshed" you mean the population-adjusted (or unadjusted) incidence of violent mortality, bipolarity has its proponents [1][2]. Unipolarity has traditionally been seen as nice in the short-run but inherently unstable in the long [Cf 3].
One point on which there is agreement, however, is the violent instability of multipolar social systems.