Citizens thoughtfully weigh the pros and cons of arguments before choosing their leaders--or so political science has traditionally assumed. Now experiments and computer models are challenging this notion, suggesting that voters tend to make emotional decisions that they rationalize afterward.

Such is the conclusion of political scientist Charles Taber of Stony Brook University and his colleagues, who have examined during the past 10 years how people decide whom they vote for. "Politics, like religion and war, is all about emotions and feelings," Taber says. "The enlightenment model of dis?passionate reason as the duty of citizenship is empirically bankrupt."