Differentiate persuasion, nudge and manipulation as instruments of social influence. Why does the line between nudge and manipulation matter for the design of welfare-scheme defaults?

Definition: Persuasion uses reasoned argument addressed to a deliberating subject; nudge re-designs the choice architecture to make welfare-aligned options easier without removing alternatives; manipulation exploits cognitive biases or information asymmetry against the subject's own interest.

Illustration: Welfare-scheme defaults illustrate the stakes. Auto-enrolment in the Atal Pension Yojana with an opt-out is a nudge — it leverages inertia for the beneficiary's benefit. The Ujjwala LPG default of choosing the subsidy-linked refill is persuasion through information disclosure. By contrast, dark-pattern designs that hide opt-out paths or exploit literacy gaps in rural enrolment cross into manipulation. Cass Sunstein's distinction turns on whether the choice architect transparently serves the chooser's reflective preferences. The Sustainable Development Goals dashboard's nudges to districts are legitimate; coercive cash-incentive linkages without disclosure are not.

Application: NITI Aayog's behavioural-insights unit follows the OECD nudge-ethics checklist, requiring transparency, reversibility and welfare-alignment before any default change in welfare design.