Abstract: Technocratic judgments can have a “cooling function.” An insistent focus on the facts, and on the likely consequences of policies, might soften political divisions and produce consensus. Within the federal government, cost-benefit analysis is a prominent example of the cooling function of technocracy. But when undertaken prospectively, such analysis is sometimes speculative and can be error-prone; in addition, circumstances change, often in unanticipated ways. For this reason, retrospective analysis, designed to identify the actual rather than expected effects, has significant advantages. The “regulatory lookback,” first initiated in 2011 and undertaken within and throughout the executive branch, has considerable promise for simplifying the regulatory state, reducing cumulative burdens, and increasing net benefits. It deserves a prominent place in the next generation of regulatory practice. Recent history also suggests that it might well soften political divisions.