In this lesson, Lawrence Summers explores two guiding principles for making and then implementing your final decision. The key is to avoid overplaying or underplaying your strategy. Learn how to think at the margin, like an economist.决策过程与实施过程中有两条指导原则：第一，不要犯不可逆的错误；第二，以一种校准的方式来思考问题。关键点就是，既不要过度依赖你的策略，也不要思考的不周全。要学会像经济学家一样思考边际这个概念。