In The Causes of War, Geoffrey Blainey argues that war occurs when nations misjudge their relative power:
He writes, “War is usually the outcome of a diplomatic crisis which cannot be solved because both sides have conflicting estimates of their bargaining power.” Disputes about issues central to states’ interests can be negotiated when there is a clear hierarchy of power—the weaker compromises to prevent war. When there is doubt about the weaker party, compromise is elusive and wars occur, because “war itself provides the most reliable and most objective test of which nation or alliance is the most powerful…war was therefore usually followed by an orderly market in political power, or in other words, peace.”
Blainey draws heavily on the work of Kenneth Boulding, especially the insight that “threat systems are the basis of politics as exchange systems are the basis of economics.” Threats keep peace as well as provoke wars. The pattern most striking to him assessing the data from three centuries of warfare is that leaders are typically optimistic commencing a war. From there, he draws the conclusion that “if two nations are deep in disagreement on a vital issue, and if both expect that they will easily win a war, then war is highly likely. If neither nation is confident of victory, or if they expect victory to come only after long fighting, then war is unlikely.” He proceeds to offer a very persuasive set of historical proofs to support it.
The economic correlation Blainey finds is particularly interesting: war is more likely to occur as optimism about an economic recovery increases. Blainey is no determinist; he sees the historical specifics as important in each war. But looking across 300 years of war and peace, he sees the greatest incidence of wars when states are confident about their future, even when others in the international order rate their futures less optimistically. World War I is, as he so wonderfully phrases it, “the haven of the theory.” Blainey quotes Bethmann Hollweg, chancellor of Germany at the outbreak of the war: “Our people had developed so amazingly in the last twenty years that wide circles succumbed to the temptation of overestimating our enormous forces in relation to those of the rest of the world.”
What makes Blainey’s book so enjoyable is that he’s a stickler for evidence. He examines the historical record and finds that many academic theories about why wars start are, simply, inaccurate. Among those theories are explanations of war as conflicts to generate national unity in times of civil strife; as opportunistic grabs for power; as excuses for economic deprivation; as means to increase economic and cultural connectedness; as caused by peace terms in a previous war; as “accidental”; and as arms races—he finds none of these theories stands up against the facts.