The logic of regulatory impact assessment: From evidence to evidential reasoning

Agencies involved in generating regulatory policies promote evidence-based regulatory impact assessments (RIAs) to improve the predictability of regulation and develop informed policy. Here, we analyze the epistemic foundations of RIAs. We frame RIA as reasoning that connects various types of knowledge to inferences about the future. Drawing on Stephen Toulmin's model of argumentation, we situate deductive and inductive reasoning steps within a schema we call the impact argument. This approach helps us identify inherent uncertainties in RIAs, and their location in different types of reasoning. We illustrate the theoretical section with impact assessments of two recent legislative proposals produced by the European Commission. We argue that the concept of “evidence-based regulatory impact assessment” is misleading and should be based on the notion of “regulatory impact assessment as evidential reasoning,” which better recognizes its processual and argumentative nature.