At least five U.S. presidential elections have been won by the second most popular candidate, but these results were not inevitable. In fact, such an unfair outcome need never happen again, and as William Poundstone shows in Gaming the Vote, the solution is lurking right under our noses. In all five cases, the vote was upset by a ''spoiler''—a minor candidate who took enough votes away from the most popular candidate to tip the election to someone else. The spoiler effect is more than a glitch. It is a consequence of one of the most surprising intellectual discoveries of the twentieth century: the ''impossibility theorem'' of the Nobel laureate economist Kenneth Arrow. His theorem asserts that voting is fundamentally unfair—a finding that has not been lost on today's political consultants. Armed with polls, focus groups, and smear campaigns, political strategists are exploiting the mathematical faults of the simple majority vote. The answer to the spoiler problem lies in a system called range voting, which would satisfy both right and left, and Gaming the Vote assesses the obstacles confronting any attempt to change the U.S. electoral system. The latest of several books by Poundstone on the theme of how important scientific ideas have affected the real world, Gaming the Vote is both a wry exposé of how the political system really works and a call to action.