Although the notion of constitutive rule has played an important role in the metaphysical debate in social and legal philosophy, several authors perceive it as somewhat mysterious and ambiguous: the idea of a specific kind of rules that are supposed to be “magically” constitutive of reality seems suspicious, more a rationalistic fiction than a genuine explanation. For these reasons, reductionist approaches have been put forward to deflate the explanatory role of this notion. In this paper, I will instead try to defend constitutive rules. My thesis is that the notion of constitutive rule is explanatorily helpful because it gives a complete account of an important phenomenon in the social and legal domain, namely, that of artifactual entities endowed with statuses that can have emergent normative properties. Conceiving of these entities as rule-constituted artifacts is an important part of what H. L. A. Hart called “the internal point of view” toward law, and for this reason constitutive rules should be included in an explanation of that point of view as an integral part of the life of institutions. The structure of my argument will be as follows. First, I will provide an example of an important phenomenon in the internal point of view, namely, the fact that individuals can have normative reactions not about the specific regulation of an institution but about its underlying purpose and rationale—what in the legal domain is called the ratio of a norm. Then I will identify two reductionistic approaches on constitutive rules. The first approach is exemplified by Brian Epstein’s idea that the phenomena explained by constitutive rules are better explained in terms of metaphysical (grounding/anchoring) relations. The second kind of reductionism is instead exemplified by the idea (held by several authors, among whom Alf Ross, Riccardo Guastini, Frank Hindriks, and Francesco Guala) that the phenomena explained by constitutive rules can be accounted for in terms of regulative rules plus a certain terminology. I will try to show that neither of these approaches can explain normative reactions to the ratio of an institution from an internal point of view: While the first cannot explain the fact that the reaction is strongly normative, the second cannot explain the fact that the reaction is about the ratio of a normative entity. Constitutive rules can instead explain both things and should be preserved as an important notion for the analysis of institutional ontology. By way of constitutive rules we create something: immaterial, rule-based institutional artifacts that can have emergent normative properties.