Geoffrey Blainey argues that wars often begin because rival nations hold conflicting assessments of their relative power. Each side may believe it possesses sufficient military, economic or political strength to achieve its objectives through conflict. When neither accepts the other’s assessment, negotiation becomes difficult and fighting may appear preferable to compromise. War, in this interpretation, arises not simply from competing interests but from incompatible expectations about who would prevail.

As a conflict develops, military outcomes, casualties and economic pressures provide evidence that can alter these expectations. Peace becomes more likely when opposing nations reach a broadly shared understanding of their relative strength and the probable consequences of continued fighting. This agreement does not necessarily resolve their underlying disagreements, but it can make negotiation more attractive. Blainey’s argument highlights the importance of perceptions and miscalculations in international relations, suggesting that the outbreak and conclusion of wars are closely connected processes.