“…I therefore invoke the robustness requirement of Bergemann and Morris (2005) so that a social choice function has to be implementable for any set of beliefs that individuals might have. Given this robustness requirement, I extend the Taxation Principle, due to Hammond (1979) and Guesnerie (1995), to show that any mechanism is equivalent to a system specifying a public good provision level and an income tax schedule as a function of the cross-section distribution of preferences, which is such that, given the public good 1 Examples are Atkinson and Stern (1974), Wilson (1991), Boadway and Keen (1993), Nava et al (1996), Sandmo (1998), Gaube (2000), Hellwig (2004), Kaplow (2006) or Gahvari (2006).…”