We live in an age of political polarization. As political beliefs on the left and the right have been pulled closer to the extremes, so have our social environments: we seldom interact with those with whom we don't see eye to eye. Making matters worse, we are being appealed to--by companies, products, and teams, for example--based on our deep-seated, polarized beliefs. Our choice of Starbucks or Dunkin' Donuts, Costco or Sam's Club, soccer or football,...