Rethinking Nudge: Not One But Three Concepts

Behavioural Public Policy, Forthcoming

HEC Paris Research Paper No. ECO/SCD-2017-1186

19 Pages Posted: 16 Jan 2017 Last revised: 14 Nov 2017

See all articles by Philippe Mongin

Philippe Mongin

GREGHEC; CNRS & HEC Paris - Economics & Decision Sciences

Mikaël Cozic

Université Paris-Est Créteil; Institut Universitaire de France

Date Written: January 1, 2017


Nudge is a concept of policy intervention that originates in Thaler and Sunstein's (2008) popular eponymous book. Following their own hints, we distinguish three properties of nudge interventions: they redirect individual choices by only slightly altering choice conditions (here nudge 1), they use rationality failures instrumentally (here nudge 2), and they alleviate the unfavourable effects of these failures (here nudge 3). We explore each property in semantic detail and show that no entailment relation holds between them. This calls into question the theoretical unity of nudge, as intended by Thaler and Sunstein and most followers. We eventually recommend pursuing each property separately, both in policy research and at the foundational level. We particularly emphasize the need of reconsidering the respective roles of decision theory and behavioural economics to delineate nudge 2 correctly. The paper differs from most of the literature in focusing on the definitional rather than the normative problems of nudge.

Keywords: nudge, liberal paternalism, policy analysis, behavioural economics, decision theory, rationality, decision biases, Thaler and Sunstein, Kahneman and Tversky

JEL Classification: D03, D18, D70, K32, K39, M38

Suggested Citation

Mongin, Philippe and Cozic, Mikael, Rethinking Nudge: Not One But Three Concepts (January 1, 2017). Behavioural Public Policy, Forthcoming; HEC Paris Research Paper No. ECO/SCD-2017-1186. Available at SSRN: or

Philippe Mongin (Contact Author)

GREGHEC ( email )

1 rue de la Libération
Jouy-en-Josas, 78350

CNRS & HEC Paris - Economics & Decision Sciences ( email )


Mikael Cozic

Université Paris-Est Créteil ( email )

61 avenue du général de Gaulle
Créteil, 94000

Institut Universitaire de France ( email )

103, bld Saint-Michel
75005 Paris
United States

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