Editor’s note: This is the 27th of 28 essays by Middlebury College Professor Emeritus Victor Nuovo on the origins of western political thought.
To characterize something as reasonable does not mean that it is delightful or pleasing. Eating ice cream or watching a movie may be delightful, but not necessarily reasonable. Having surgery is reasonable, when it is necessary to save your life; likewise, dieting, swallowing bitter medicine, exercising, and also morality and politics may be reasonable, though not necessarily pleasing.
Madison may have borrowed from Locke the idea of the sovereignty of the people and used it to establish the authority of the constitution. But he sided more with Machiavelli and Hobbes with regard to the human character. He preferred their realism, shared their views of human nature, agreed with them about the origin and nature of law and its necessity. These features of his thinking become clear in his writings in defense of the Constitution.
Begin with human nature. Madison agreed with Hobbes that a state of nature is a state of war of all against all, a lawless state, and that peace and civility would occur only if people covenanted together to form a civil society. To that end, the means would be to establish a constitution, a fundamental law. This system of government must be so designed “that its several constituent parts may, by their mutual relations, be the means of keeping each other in their proper places.”
Madison went on to make this most memorable and quotable observation:
“But what is government 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 enable the government to control the governed; and in the next place oblige it to control itself. [The Federalist no. 51]
A principal means of government self control is the separation of powers. The power of government is divided or separated into three branches: legislative, which makes the laws; executive, which puts them into operation; and judiciary, which interprets the laws and policies of the other two branches, and has the power to decide on their constitutionality. Neither branch is to encroach upon the other; rather each is to be separate and independent with “a will of its own,” jealous of its particular prerogatives, endowed by law with “separate and rival interests.”
These interests become potent when they combine the personal with the institutional. The constitutional rights and duties of the office become incarnate in the person who occupies it. Selfish motives are institutionalized, the vices of human nature become instruments of public legality, even public virtue, and the powers of government are corralled and directed to achieve a common good. This idea would seem perverse, if it were not resplendent in practical wisdom.
In another place [The Federalist no. 10], Madison offers a similar defense of the American Constitution. He laments that civil societies tend to fragment into factions or communities joined together and driven by a common impulse or passion or interest, which are opposed to the rights of other groups and to the common good. These special interests may be derived from religious, social, political, or economic motives: evangelical zeal, the ambition of aspiring politicians, partisan self interest, identity politics, the conflicting interests of rich and poor, of creditors and debtors.
The question is how to deal with this condition. One way would be to remove its causes. Factions are voluntary associations. What if individuals were prohibited from forming a faction? That would seem to be the most effective solution, for “Liberty is to faction, as air is to fire,” remove the one, and the other will quickly die. But this would be sheer folly, if not suicidal, for just as air is essential to animal life, liberty is essential to political life, and political life is a necessity. And in any case, as Locke proved, it is impossible to change beliefs by force or coercion.Another way would be by creating unanimity of opinion and sentiment through universal education, to homogenize the people by indoctrinating them. But this is to assume that we can be certain that the opinions we propose to teach are true, which is a false assumption, or that human identities and their commitments can be changed at will. Besides, this would subvert the very purpose of education, which is never to indoctrinate, but to foster a love of truth and a passion for free enquiry.
Spinoza is right: freedom to seek the truth and follow it wherever it leads must never be abridged; to remain healthy, a republic requires a regular tonic of truth.
Besides, it would seem that the causes of faction are inherent in human nature. Human nature may be sociable, but human fallibility and selfishness and limited horizons, more often cause us to prefer the society of others like ourselves, who share our prejudices. Factions, like evils, must come. 
So long as a faction is a minority, the will of the majority should be sufficient to defeat its purposes if they threaten the common good. But what if a faction should grow into a majority? This is not an idle concern. If political parties count as factions, then, when one party controls all the branches of government, the possibility of tyranny of the majority becomes real, perhaps imminent.
Madison’s response is that it is the very nature of the American republic to be armed to counteract this outcome. He did not conceive of our republic as a homogeneous city, but as an expanding union soon to embrace a continent. And although he did not use the term “diversity,” he seems to have anticipated the necessity of it. The key was a combination of social diversity and a fundamental law, which provides that the branches of government and its institutions function competitively, and which subjects even the authority of “the People” to a rule of a law that even they cannot revoke, although they may amend it.
This is the design of our nation: a nation established by fundamental law, the Constitution, which prescribes the separation of powers as a safeguard against tyranny and for the same reason requires that its officials in the legislative and executive branches hold tenure for a limited period, subject to the will of the people.
Will it work? One thing more was needed. Madison expected that over time a deep respect for law would take root in the minds of the people and the public officials who serve them, that reverence for the rule of law would take root in the soul of the nation, and that our civil society would grow into a self-sustaining living thing.
Was this a proper expectation, or merely a hope? The answer is what the so-called American experiment is supposed to reveal.