Peace does not simply preserve itself. If Donald Kagan is right, and the secret of the human species is our ability to learn from our experience, look forward to assess likely futures, and apply the lessons we have learned, then surely there can be few lessons greater than how we might keep the peace between nations. As Thucydides remarked, and Kagan agrees, there is a very thin line which separates the civilized from the uncivilized, and that line requires careful attention if we are not to slip into folly.Kagan's work looks at five crisis throughout western history, the Peloponnesian War, World War I, the Second Punic War, World War II, and the Cuban Missile Crisis, to investigate the common factors which brought about the first four and what was different about the fifth - as a sort of "control." Providing an analysis of the major events and players that led to the outbreak of hostilities he draws lessons from the past that we might apply in the future. Primarily he echoes the tripartite reasoning employed by Thucydides, that states engage in conflict primarily out of honor, fear, and interest. This assessment is crucial because it holds that wars often occur for reasons that transcend the simply rational. This is not to suggest that all war is specifically irrational, but rather that someone looking for a reason-based account of why different states have acted as they have will be left wanting.
Sometimes for better, but mostly for worse, war has been an almost continuous part of the human experience. Kagan's work strives to remind us that simply because the West inhabits a relatively peaceful present this is no assurance that our lives will be free of conflict. He warns against the kind of naivete that characterized 1930s Britain: that recognizing that war was horrible and earnestly desiring to never engage in another does not preclude being drawn into a defense of one's country. To blithely assume that humans have somehow progressed beyond war is to run the risk of a certain ignorance of that which we have in common with our forebears. Learning from the past need not mean celebrating it. We pay the greatest respect to the horrors of war by studying it closely. To earnestly say, "never again" we must appreciate exactly what we mean by "again." When the specter of war disappears entirely, when we ignore the lessons of the past, that is when we are in the greatest peril.
