Preface -- Executive summary -- I. The democratic peace : an important piece of the puzzle -- II. More pieces of the puzzle : government structures and the effect of internal incentives -- III. More pieces II : the path to war--are democracies as aggressive as nondemocracies? -- More pieces III : deterrence and the effect of external incentives -- V. Democracy and deterrence : a first-stage hypothesis -- VI. Testing the hypothesis -- VII. Building on other approaches -- VIII. Toward incentive theory : understanding and refining the hypothesis -- IX. September 11 and its aftermath : terrorism, Afghanistan, and the Iraq War -- X. Consequences for foreign policy -- XI. A future with fewer wars -- Notes -- annex I. Graphic representaton of incentive theory in war/peace decisions -- annex II. Illustrative methodology for measuring deterrence -- annex III. Major interstate wars since adoption of the United Nations charter -- annex IV. Major interstate wars of the United States -- Works cited -- About the author -- Index.