ferson noted this while reflecting on the tiny incentive that led to the Boston Tea Party and, in turn, the American Revolution: "So in- scrutable is the arrangement of causes and consequences in this world that a two-penny duty on tea, unjustly imposed in a sequestered part of it, changes the condition of all its inhabitants."   In the 1970s, researchers conducted a study that, like the Israeli day-care study, pitted a moral incentive against an economic incen- tive. In this case, they wanted to learn about the motivation behind blood donations. Their discovery: when people are given a small stipend for donating blood rather than simply being praised for their altruism, they tend to donate less blood. The stipend turned a noble act of charity into a painful way to make a few dollars, and it wasnt worth it. What if the blood donors had been offered an incentive of $50, or $500, or $5,000? Surely the number of donors would have changed dramatically. But something else would have changed dramatically as well, for every incentive has its dark side. If a pint of blood were suddenly worth $5,000, you can be sure that plenty of people would take note. They might literally steal blood at knifepoint. They might pass off pig blood as their own. They might circumvent donation limits by using fake IDs. Whatever the incentive, whatever the situation, dishonest people will try to gain an advantage by whatever means necessary. Or, as W. C. Fields once said: a thing worth having is a thing worth cheating for.       Who cheats? Well, just about anyone, if the stakes are right. You might say to yourself, I dont cheat, regardless of the stakes. And then you might re- member the time you cheated on, say, a board game. Last week. Or