Paper by Arden Rowell: “The nudge – a form of behaviorally-informed regulation that at-tempts to account for people’s scarce cognitive resources – has been explosively successful at colonizing the regulatory state. This Essay argues that the remarkable success of nudges as a species creates new challenges and opportunities for individual nudges that did not exist ten years ago, when nudges were new. These changes follow from the new fact that nudges must now interact with other nudges. This creates opportunities for nudge versus nudge battles, where nudges compete with other nudges for the scarce resource of public cognition; and for nudge & nudge symbiosis, where nudges work complementarily with other nudges to achieve greater good with fewer resources. Because of the potential for positive and negative interactions with other nudges, modern nudges should be expected to operate differently from ancestral nudges in important ways, and future nudges should be expected to operate more differently still. Policymakers should prepare to manage future positive and negative nudge-nudge interactions….(More)”.