Modularity, identity, and the constitutional diagonal
将模块化系统框架应用于社会制度，研究身份认同产生的无形外部性如何通过身份群体模块化和宪政对角线治理结构来内部化，并探讨其对大型社交网络（如Facebook）的启示。
Abstract The framework of modular systems articulated in Design Rules can be applied in the larger setting of social institutions. The principles of encapsulation and information hiding operate in society as mechanisms to internalize externalities. This essay focuses on intangible externalities, or “moralisms,” that involve the transmission across module boundaries of pure information rather than materials or energy. Such intangible externalities arise in the practice of identity, the affiliations through which individuals create and define their sense of self. Both formally and informally, individuals tend to modularize themselves into identity groups in order to minimize the costs of the intangible externalities that identities impose on one another. One important way to reduce conflict among identity groups is to create a governance structure in which some interactions are proscribed—the constitutional diagonal. In the end, because of the inherent incompatibilities—the non-modular interactions—between identities that arise inevitably from the very meaning and function of identity, genuine toleration is possible only through the increased standardization of identities. The essay applies these ideas to the problems facing large social networks like Facebook.