"Ambition must be made to counteract ambition. The interest of the man must be connected with the constitutional rights of the place. It may be a reflection on human nature, that such devices should be necessary to control the abuses of government. But what is government itself, but the greatest of all reflections on human nature? If men were angels, no government would be necessary. If angels were to govern men, neither external nor internal controls on government would be necessary. In framing a government which is to be administered by men over men, the great difficulty lies in this: you must first enable the government to control the governed; and in the next place oblige it to control itself. A dependence on the people is, no doubt, the primary control on the government; but experience has taught mankind the necessity of auxiliary precautions."In arguing for the government to control itself, Madison laid out a system with a separation of powers with two different legislative houses; an executive branch headed by a separately elected president; and an appointed-but-subject-to-confirmation judicial branch. The idea wasn't new to Madison, of course. Arguments for the separation of legislative and executive are made in John Locke's (1690) Second Treatise on Government, although Locke tended to view the power of judging, via magistrates, as an offshoot of legislative power. Montesquieu is often credited with the the first explicit division of governing powers into legislative, executive and judiciary in his 1748 book The Spirit of the Laws. For example, Montesquieu writes (in translation) in Book XI, Chapter 6:
When the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty; because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws, to execute them in a tyrannical manner. Again, there is no liberty if the judiciary power be not separated from the legislative and executive. Were it joined with the legislative, the life and liberty of the subject would be exposed to arbitrary control; for the judge would be then the legislator. Were it joined to the executive power, the judge might behave with violence and oppression.Economics is not willing to assume that angels are taking human form--not among business executives, workers, consumers, taxpayers, voters, nor among who are elected, appointed, or hired to government posts. It can feel frustrating when society and government seems to struggle against itself and may even become unable to act, with conflicts between branches and their differentiated responsibilities. But the alternative of a government in which acts without such constraints is, at least to me, a considerably less attractive prospect.