Michael sander is a political philosopher and a professor at Harvard University. Professor Sandel has offered the general education course "Justice" in Harvard for more than 30 years, and is known as the "legendary course" of Harvard. In 2005, his course video was put into the online classroom of Harvard Open University, and his influence expanded from Harvard classroom to the whole world. In recent years, with the domestic "translation team" producing Chinese subtitles for international online classes, Sandel's fans in China have multiplied rapidly. The topic of Professor Sandel's lecture is "Fairness, what should be done?" As soon as he came up, he puzzled the audience with several problems: if you are the driver of an out-of-control tram, there are five people in front; Towards the end, I found a fork, and there was a man on the other side of the fork; What would you do? Go straight and kill those five people? Or turn around and kill another person? After getting the audience's initial answer, he further questioned the basis of his argument, and guided everyone to experience and think step by step by questioning each other and reflecting on his original position. Fair, what should I do? He encourages students to defend their opinions, which often leads to lively and humorous classroom discussions.