It is convenient to think that China, Russia and terrorism represent our greatest threats. While they are important, our greatest threats are tribalism and the national debt — and they are getting worse.

In 1992, the late historian Arthur Schlesinger wrote “The Disuniting of America.”  He explored and explained how separatism nourishes prejudices and stirs antagonisms. Where America was once seen as the great melting pot with a unifying identity, we are witnessing a proliferation of special interest tribes —  groups whose behavior, rhetoric and attitudes stem from loyalty to the group’s identity. Historian Diane Ravitch has written that history should “help us understand how bonds of cohesion make us a nation rather than as irascible collection of unaffiliated groups.” The lack of unifying cohesive forces is a source of numerous problems, including political polarization.

Today, tribes ranging from evangelicals to extreme ethnic and religious groups, to pro-life/pro-choice, to supremacists and socialists seek special benefits and treatment. Parochial interests can undermine the idea of a coherent society. Tribes in their actions reject our basic principles that envision an open society built on tolerance and respect. The assemblage of grievance collectors, promote exclusion and expend energy on what divides us and not what unites us.

In “The End of the Experiment,” the preeminent political scientist Stanley Rothman argues that the nation’s founders saw the republic as uniquely fragile since it is based on values rather than tribal loyalties. “Government legitimacy depends on acceptance of Calvinist values, including success through work, love of God rather than self, universalism rather than narrow tribalism, integrity in public and private interactions, and restraining individual passions.”

Loyalties are becoming narrower and tied to political correctness and intolerance.  The Atlantic published an article “Congress Has a Caucus for Everything” The fragmentation reflected in these groups helps to explain why members cannot find common ground on a range of important matters of national importance. Instead of making the national debt a unifying priority, Congress panders to expanding special interests — tribes that seek more and more favors and that have an increasing list of grievances.

In the years after World War II through the 1970s, there was a steady decline in the national debt as a percentage of GDP.  From a low of 31 percent, it has steadily climbed to today’s level of 106 percent, which is more than $22 trillion.

Economists and organizations like the Peterson Institute and the Concord Coalition routinely warn about the dangers of our growing debt. But no one who can make a difference is listening. Members of Congress want to get re-elected and that comes from granting favors; not telling voters to eat their spinach.

In their book “This Time is Different,” Ken Rogoff and Carmen Reinhart examine more than 200 instances of national debt crises. In each case, the nations involved were able to borrow money until the “Bang Moment,” the point where bond market doesn’t function. When the national debt becomes so large that debt servicing becomes an issue, lenders ask for higher returns, which only add to the debt unless spending controls are put in place. Otherwise the bond market collapses, according to most economists.

With entitlement programs along with debt servicing consuming more than 70 percent of federal spending, it is hard to lay out an only mildly painful course of action to reduce the debt to a more acceptable level. Tribes, especially the elderly, will resist any reductions in what they consider their fair share and almost everyone will resist inevitable tax increases.

Senator Elizabeth Warren has proposed an additional tax on the super-wealthy claiming that it would raise almost $3 trillion over 10 years. But based on the French experience with a wealth tax, the actual amount raised would be about one-half that.  Even if all of the revenue raised was dedicated to deficit reduction, its effect would not be large. In addition, there are questions about the constitutionality of such targeted taxes.

These twin threats suggest a bleak future for our children and grandchildren unless somehow our political system rights itself. Unfortunately, the polarization in Congress that reflects the fragmentation in society makes that very unlikely.