This book would not have been possible without the interactions with our students at Columbia University, the Institut d’Etudes Politiques de Paris, and Ecole Polytechnique Paris. They had previously graduated in all kinds of subjects, and they were all new to the approach taken here. That required us to make constant effort to clarify both our conceptual clarity and our pedagogy, as well as to achieve an appropriate balance among conceptual developments, illustrations, and applications. These efforts should make the book accessible and attractive to larger audiences of readers interested in the issues discussed.

如果没有与哥伦比亚大学、巴黎政治学院和巴黎理工学院学生的互动，这本书就不可能问世。他们以前毕业于各种学科，对这里采取的方法都是全新的。这要求我们不断努力澄清我们的概念清晰性和教学法，并在概念发展、说明和应用之间取得适当的平衡。这些努力应该使这本书易于阅读，并吸引更多对所讨论问题感兴趣的读者。