Why do people become firemen, policemen, soldiers, freedom fighters, all activities that cannot be explained in terms of self-interest alone?

不可能只用拿工资的理由，就能完全解释为什么总有人愿意做,消防员，警察，军人和争取自由的斗士？

耶鲁公开课 - 政治哲学导论课程节选