A last word in my debate with Michael Abramowicz. He presents the choice between predictocracy and futarchy as a choice between errors in choosing values and errors in estimating consequences: Hanson makes some strong points in favor of futarchy. “Democracy today suffers from enormous errors regarding estimates of policy consequences.” … Ex post evaluators in predictocracy might make some systematic errors that prediction market traders in futarchy would fix. Futarchy, however, introduces another type of error, the danger that the legislature will not do a good job of defining GDP+, as Hanson acknowledges. It’s not a priori clear which would be worse — errors by the legislature in developing a formula for GDP+, or errors by ex post evaluators in determining whether a particular policy has increased or decreased general welfare.