Psychiatric nosology entails a complex combination of descriptive and prescriptive elements. While there has been a great emphasis upon developing empirical evidence to guide the further development of nosology, scant attention has been given to normative questions of what nosology ought to accomplish. A largely neo-Kraepelinian view of nosology has guided the DSM-5 revision process. The normative suppositions of the neo-Kraepelinian view remain largely implicit but, when made explicit, it becomes clear that they are contestable and lack proper justification. This chapter invokes the neo-Kantian philosophical work of Jurgen Habermas in order to address the normative issues at stake in nosology. Habermas establishes a procedural notion of normative validity that would safeguard normative issues in nosology from being resolved in an arbitrary or coercive manner. This procedural notion of normative validity clarifies the significance of integrating the perspectives of patients in order to determine what nosology should accomplish. The fact that normative issues form an essential part of nosology means that we should remain skeptical toward any claims for the validity of the science that ignore the normative dimension of the science while attending solely to empirical issues.