– Executive Summary –

Nudge theory exploded onto the academic and policy scene in 2008 with Richard Thaler and Cass Sunstein’s seminal book, Nudge.[1] In it, they argue that an individual can improve people’s choices by altering the contextual decisional environment to nudge said people towards a more positive outcome or choice.[2] They further argue that policymakers should nudge individuals in alignment with a novel ethical framework, “libertarian paternalism.”[3] As Thaler and Sunstein present it, libertarian paternalism is more or less the idea that an intervention (a nudge) should not limit people’s absolute abilities to make a choice (their liberty) and that such nudges should guide people to make choices they themselves would judge to be better (i.e., the decision-maker views the nudged decision to be in her best interests).[4]

Much hope and optimism has sprung from nudge theory and libertarian paternalism regarding their potential to improve various policy problems. Entire “nudge units,” such as the Behavioral Influence Team based in the United Kingdom, have been created to tackle a host of policy problems in various contexts across the world.[5] However, it is unclear whether nudge theory has significantly percolated into the consciousness and practices of homeland security practitioners and policymakers. In addition, to the extent homeland security nudges have been used, whether they are effective. To better assess these questions, this thesis conducted a systematic and gray literature search, presented in Chapter II, for actual usages of nudges in homeland security contexts.

This search resulted in six nudge studies related to homeland security. This small number relative to nudge theory’s popularity outside the field provides some evidence nudges are not being readily used in homeland security. Nevertheless, four key takeaways distilled from the literature were relevant to homeland security practitioners/policymakers utilizing nudges in their specific contexts: nudge interventions have varying effectiveness and outcomes in homeland security contexts; no dominant nudge taxonomy or framework exists; nudges can be used on various populations; and certain types of nudges appear more likely to be used than others.

These takeaways, in combination with the limited number of actual homeland security nudges, set up an important follow-up question. Namely, can nudge interventions be successfully implemented across the homeland security domain (i.e., can nudges be effective in various homeland security contexts)? Chapter II empirically explored this question and found the answer to be inconclusive. Chapter III then conceptually examined the same question by exploring general nudge effectiveness.

Three different avenues of pursuit shaped the exploration of general nudge effectiveness. First, various nudge frameworks created with the purpose of helping public practitioners/policymakers create effective nudge interventions were explored. Second, recent meta-analyses and scoping reviews related to nudge effectiveness were analyzed for possible takeaways. Third, known limitations to nudge effectiveness were discussed.

This approach provided three takeaways for homeland security practitioners/‌policymakers. First, the results suggest a qualified but optimistic “yes” to the question of whether nudges can be effective in homeland security. Second, the exploration provided a foundational understanding of the current evidence of general nudge effectiveness. Third, the analysis provided grounds to better think about how and where nudges might be effective and warranted in one’s specific context(s).

The third key takeaway, specifically, the grounds to better think about how and where nudges might be effective in homeland security, was further buttressed by a four-question effectiveness framework developed in this thesis. The framework requires the practitioner/policymaker to examine, relative to their homeland security problem, which heuristics and biases are at play, what nudge framework should be used in creating the nudge, which nudge categories should be applied, and which nudge limitations are likely to exist. Responding to this four-question framework should improve the likelihood that a nudge intervention in a homeland security context would be effective.

However, whether a nudge is effective is not the only question to consider. An equally if not more important question is whether nudges, assuming they can be effective in homeland security contexts, should be utilized. This thesis explores the ethics of nudges and the associated ethical framework, libertarian paternalism. In particular, it explores critical related ethical issues and concludes that the jury is still dispositive with respect to whether nudges are generally ethical. However, understanding that nudges are to some extent already being utilized and may be used in the future, this thesis provides a homeland security–specific ethical framework to guide practitioners/policymakers in determining whether a proposed nudge intervention would be ethical.

The ethical framework is composed of six questions: Is the proposed intervention a mandate, a ban, coerce, or otherwise provide significant positive or negative incentives to the individual(s) targeted? Is the proposed intervention intended to promote the welfare of the individual(s) targeted? Is (are) there reasoning failure(s) at play? Does the proposed nudge need to be secret? Does the proposed nudge violate autonomy, dignity, and/or self-government? Is the proposed nudge intervention the most effective policy to promote the individual’s(s’) welfare relative to other possible interventions? After answering these six questions, homeland security practitioners/policymakers can be more confident that their proposed intervention is in fact a nudge and ethical.

The conclusion suggests opportunities for future research including the conceptual and experimental testing of the four-question effectiveness framework and six-question ethical framework developed in this thesis. It further argues there is ample opportunity for careful exploration, creation and testing of nudge interventions in homeland security contexts. Any experimentation should preferably have its process meticulously documented, should be implemented with a randomized controlled trial, and the evidence should be gathered and shared with the broader homeland security community.


[1] Richard Thaler and Cass Sunstein, Nudge: Improving Decisions about Health, Wealth, and Happiness (New York: Penguin Books, 2009).

[2] Thaler and Sunstein, 3–4.

[3] Thaler and Sunstein, 5.

[4] Thaler and Sunstein, 5.

[5] David Halpern, Inside the Nudge Unit: How Small Changes Can Make a Big Difference (London: Penguin Random House, 2015), 8.

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