Robin Hahnel has argued that "participatory planning is not central planning", stating "The procedures are completely different and the incentives are completely different. And one of the important ways in which it is different from central planning is that it is incentive compatible, that is, actors have an incentive to report truthfully rather than an incentive to misrepresent their capabilities or preferences." Unlike historical examples of central planning, the parecon proposal advocates the use and adjustment of price information reflecting marginal social opportunity costs and benefits as integral elements of the planning process. Hahnel has argued emphatically against Milton Friedman's a priori tendency to deny the possibility of alternatives: