Our central empirical claim here has been that in many domains, people’s preferences are labile and ill-formed, and do not predate social and legal contexts. For this reason, starting points and default rules are likely to be quite sticky. Building on empirical work involving rationality and preference formation, we have sketched and defended libertarian paternalism — an approach that preserves freedom of choice but that encourages both private and public institutions to steer people in directions that will promote their own welfare.
Some kind of paternalism, we believe, is likely whenever such institutions set out default plans or options. Unfortunately, many current social outcomes are both random and inadvertent, in the sense that they are a product of default rules whose behaviorshaping effects have never been a product of serious reflection. In these circumstances, the goal should be to avoid arbitrary or harmful consequences and to produce contexts that are likely to promote people’s welfare, suitably defined.
Cass Sunstein, Richard Thaler (2006) ‘Preferences, Paternalism, and Liberty’ http://journals.cambridge.org/abstract_S135824610605911X