James M. Buchanan (1919–2013) was notable for his contributions to different fields of Economics, being awarded with the Nobel Memorial Prize in this area in 1986. His methodology is characterized by three fundamental aspects: methodological individualism, a constitutional approach, and a contractarian political philosophy. In this paper, we explore the development of these features in Buchanan’s works and contrast them with alternative classifications in these categories by scholars in other areas of knowledge. We show that Buchanan’s individualism uses a concept of homo economicus that differs from most of his peers in economics. His constitutionalism follows a specific strand that differs from other constitutionalists of political science and law, and leads to his contractarianism, which also has its particularities within political philosophy and ethics.

James M. Buchanan (1919–2013) 因其对经济学不同领域的贡献而著称，并于 1986 年获得该领域的诺贝尔纪念奖。他的方法论具有三个基本方面的特征：方法论个人主义、宪法方法和契约论的政治哲学。在本文中，我们探讨了布坎南作品中这些特征的发展，并将它们与其他知识领域的学者在这些类别中的替代分类进行了对比。我们表明，布坎南的个人主义使用了与他的大多数经济学同行不同的经济人概念。他的宪政遵循不同于其他政治科学和法律宪政主义者的特定路线，并导致他的契约主义，