On Preferring A to B, While Also Preferring B to A

Forthcoming, Rationality and Society

Harvard Public Law Working Paper No. 18-13

25 Pages Posted: 5 Mar 2018 Last revised: 6 Jun 2018

See all articles by Cass R. Sunstein

Cass R. Sunstein

Harvard Law School; Harvard University - Harvard Kennedy School (HKS)

Date Written: March 21, 2018


In important contexts, people prefer option A to option B when they evaluate the two separately, but prefer option B to option A when they evaluate the two jointly. In consumer behavior, politics, and law, such preference reversals present serious puzzles about rationality and behavioral biases. They are often a product of the pervasive problem of "evaluability." Some important characteristics of options are difficult or impossible to assess in separate evaluation, and hence choosers disregard or downplay them; those characteristics are much easier to assess in joint evaluation, where they might be decisive. But in joint evaluation, certain characteristics of options may receive excessive weight, because they do not much affect people's actual experience or because the particular contrast between joint options distorts people’s judgments. In joint as well as separate evaluation, people are subject to manipulation, though for different reasons. It follows that neither mode of evaluation is reliable. The appropriate approach will vary depending on the goal of the task – increasing consumer welfare, preventing discrimination, achieving optimal deterrence, or something else. Under appropriate circumstances, global evaluation would be much better, but it is often not feasible. These conclusions bear on preference reversals in law and policy, where joint evaluation is often better, but where separate evaluation might ensure that certain characteristics or features of situations do not receive excessive weight.

Suggested Citation

Sunstein, Cass R., On Preferring A to B, While Also Preferring B to A (March 21, 2018). Forthcoming, Rationality and Society, Harvard Public Law Working Paper No. 18-13, Available at SSRN: https://ssrn.com/abstract=3132428 or http://dx.doi.org/10.2139/ssrn.3132428

Cass R. Sunstein (Contact Author)

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Harvard University - Harvard Kennedy School (HKS) ( email )

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