麻省理工学派则针锋相对地指出真实世界经济普遍受到市场失灵的困扰，包括不完全竞争和垄断，以及与污染、无法提供街道照明或国家防御等公共必需品等问题相关的外部缺陷。
The MIT School, by contrast, argues that real-world economies are afflicted by pervasive market failures, including imperfect competition and monopoly, externalities associated with problems like pollution, and an inability to supply public goods such as street lighting or national defense.