Résumé (EN)

We study a legislature where decisions are made by playing an agenda-setting game. Legislators are concerned about their electoral prospects but they are also genuinely concerned for the legislature to make the correct decision. We show that when ideological polarization is positive but not too large (and the status quo is extremely inefficient), institutions in which the executive has either no constraints (autocracy) or many constraints (unanimity) are preferable to democracies that operate under an intermediate number of constraints (simple majority rule). When instead ideological polarization is large (and the status quo is only moderately inefficient), simple majority turns out to be preferable.