Geoffrey Blainey argues that wars often begin because opposing nations hold incompatible expectations about how a conflict will unfold. Each side may anticipate victory, underestimate the resistance it will encounter or believe that fighting will be relatively brief. These conflicting predictions make compromise difficult, as neither government sees sufficient reason to abandon its objectives. War becomes possible when both sides believe their expectations justify the risks of military confrontation.

As fighting continues, battlefield outcomes, mounting costs and changing circumstances provide evidence that can challenge these initial assumptions. Governments may gradually develop more similar assessments of their relative strength, the likely duration of the conflict and the prospects of victory. When their expectations converge, the advantages of continued fighting become clearer, potentially creating conditions for negotiation and settlement. Blainey’s argument suggests that ending wars depends not only on military developments but also on changes in how opposing nations understand their situation and evaluate their remaining options.