The great Arabic historian Ibn Khaldun seized upon the Arabic word asabiyyah to characterize what he considered to be the central attribute of a successful society. The term has a number of related meanings, the most common of which is "social solidarity". It describes the sense of unity in a society. In a more nationalistic sense, it might be interpreted as "patriotism", but that term can be used divisively, where asabiyyah emphasizes solidarity. Economists have a version of the term that emphasizes economic productivity: social capital. This is the degree to which citizens trust each other. Low social capital imposes all manner of economic costs upon a society: more locks, stronger doors, more police, more prisons, longer contracts, fewer handshake deals, more conflict.

High levels of asabiyyah are always associated with success as a society, and low levels always portend decline. The Roman Republic enjoyed very high asabiyyah, as demonstrated by the story of Gaius Mucius Scaevola, ( Later, as the Gini Index ( rose higher during the Empire, asabiyyah evaporated and the Empire collapsed.

The Japanese had extremely high levels of asabiyyah, as exemplified in their cheer "Bonsai! Bonsai! Bonsai!". That is not a war cry; it is a statement of social solidarity. It means something like "One for all, all for one!" That asabiyyah enabled what was a third-world country to transform itself in less than a hundred years into a world power. The velocity of their success went to their heads and brought disaster down upon them, but they recovered and are now one of the great economic powers of the world. 

The fundamental force at work is an egalitarianism that is burned into our genes. Humans expect to be treated fairly. Not just humans; even simians share this expectation. See for a hilarious example of this expectation. People react violently to perceived unfairness. 

Note that I am talking about perceived unfairness. There is no reliable specification of objective fairness; it is an intrinsically subjective matter. Wealthy people often insist that the poverty of others is their own fault; the economy gives everybody a fair opportunity to prosper. That declaration cannot be supported objectively; it is a matter of opinion. Poor people beg to differ. 

Therein lies a massive social problem. Large disparities in wealth always create the perception of unfairness. After all, can you honestly say that a businessman worth, say, a billion dollars, has been a million times more productive than a janitor with a net worth of a thousand dollars? Sure, the businessman worked harder and made better decisions than the janitor -- but was his contribution to society truly a million times greater? I find that hard to believe. More important, a great many poor people find it hard to believe. 

I want to emphasize the subjective nature of this perception. You can argue all day long that the businessman truly does deserve to be a million times richer than the janitor, but that is irrelevant to the point I am making: that all those poor people perceive their situations to be unfair. Right or wrong, they don't like it.

This brings us back to asabiyyah: why should any poor person in this society feel the slightest sense of solidarity with it? Why should any poor person play by the rules of a society that is obviously (in their own eyes) unfair? This loss of confidence in "the system" is now extending to the lower middle classes. Their votes for Mr. Trump were a gigantic middle finger extended at the entire system. They are so angry at the unfairness of the system that they want to tear the whole thing down. The right-wingers blame all the troubles on the leftist aspects of the system; the left blames all the troubles on the right-wing aspects of the system. 

Historically, one of America's big economic advantages has been its high level of social capital; I am sad to say that America's social capital is rapidly declining. Mr. Trump is greatly accelerating the process. To foster asabiyyah, a leader should always emphasize our common values. Mr. Trump takes the opposite tack, constantly attacking different components of our society: the courts, the FBI, Democrats, Muslims, immigrants... the list is long. Every time he attacks somebody, he destroys some asabiyyah. He is doing the opposite of making America great; he is tearing it apart. 

Few modern Americans realize just how close this country teetered on the edge of revolution in the early 1930s. Communism was still admired by many leftists because the truth of the Soviet Union had not yet clearly emerged. It was obvious to everybody that capitalism had failed spectacularly, and millions of discontented people voiced their anger at a system that had failed them. Mr. Roosevelt was able to push through Congress huge changes in the social structure; his achievement was partly due to his ability to convince the wealthy that without such changes, the country might suffer a revolution which would destroy all their wealth. 

A society with low asabiyyah does not simply collapse; it gives warnings long before catastrophe strikes. Crime rates rise -- why should you obey the system's rules when the system cheats you? Politics becomes a struggle for raw power rather than a cooperative effort to improve the country. Individual acts of mindless violence increase in frequency; the generalized sense of being treated unfairly sometimes erupts in random acts of pure hate. If the situation festers for too long, violence becomes generalized and a revolution arises. Such a revolution is neither organized nor directed at any particular goal; it is instead an outpouring of frustration with everything. Most revolutions are eventually taken over by the most politically astute rabble-rousers and directed toward their own ends. 

I close with a long quote from the great historian Will Durant:

"Since practical ability differs from person to person, the majority of such abilities in nearly all societies, is gathered in a minority of men. The concentration of wealth is a natural result of this concentration of ability, and regularly recurs in history. The rate of concentration varies (other factors being equal) with the economic freedom permitted by morals and the laws. Despotism may for a time retard the concentration; democracy, allowing the most liberty, accelerates it... In progressive societies the concentration may reach a point where the strength in number of the many poor rivals the strength of ability in the few rich; then the unstable equilibrium generates a critical situation, which history has diversely met by legislation redistributing wealth or revolution redistributing poverty."

Redistribution of wealth is not an act of charity; it is necessary to the survival of every society with a high Gini Index. You may rant that it is not fair or proper, but without it, a great many more people will rant that the system is not fair or proper. Think of it as social hygiene.