The Justification of Bicameralism

The main disadvantage of unicameral legislatures operating by simple majority rule is that, when politics is two-dimensional, they allow the adoption of out-of-equilibrium policies. Since in such cases a majority opposed to what a majority has adopted, the result is majority tyranny. To minimize such tyranny, it is necessary to delay action until a true majority in society is arrived at. Of the several methods of delay — supermajorityism, multipartyism, multicameralism — the best is multicameralism because it allows for simple majority rule when politics is one-dimensional (and hence when a median voter equilibrium is likely to exist) yet discourages decision when politics is two-dimensional (and hence when, almost certainly, no equilibrium exists).