Hume's Second-Best Constitutionalism

In the economic and political science literature on constitutional choice and constitutional design, David Hume is almost invariably associated with a master principle of design that is congenial to rationalactor approaches. I shall call this the knavery principle. As Hume put it, "in contriving any system of government, and fixing the several checks and controuls of the constitution, every man ought to be supposed a knave, and to have no other end, in all his actions, than private interest."' The knavery principle is, however, untenable, as I shall subsequently discuss. So it might seem that Hume has nothing valuable to tell us about constitutional design. My concern here is to dispel that impression, and by so doing to reevaluate and vindicate Hume's contributions. I shall argue that Hume's principal contribution is not the knavery principle. Indeed one of his major claims about the British constitutional order was that it violated the principle, and one of his major projects was to explain how the mixed British constitution could nonetheless retain its stability. Hume's real contribution, rather, is to have pioneered the critical idea of second-best constitutionalism: the idea that multiple departures from the optimal or first-best constitutional arrangements might offset each other, producing compensating adjustments that ensure constitutional equilibrium. Hume's characteristic mode of analysis, I shall suggest, is simultaneously to identify both a departure from optimal constitutional design and an offsetting institutional adjustment that compensates for the initial defect.