Negotiators—whether politicians or homebuyers—begin with bold concessions which rapidly shrink the gulf between opposing sides. But like curves approaching an asymptote in geometry, as they near an agreement they level off and struggle to bridge the final, though trivial, gap. The effect of their ongoing quarreling is that, by the end, their motivating goal is not so much to strike a deal or make a sale as to make the other side yield, on no matter how minor a point. The fact of winning a concession...