In retrospect, the civil war in the Balkans was the most important event of that period. It prefigured what has come since: the return of ethnic separatism, the rise of authoritarian populism, the retreat of liberal democracy, the elevation of a warrior ethos that reduces politics to friend/enemy, zero-sum conflicts.

.. Back in the 1990s, there was an unconscious abundance mind-set.

.. Today, after the financial crisis, the shrinking of the middle class, the partisan warfare, a scarcity mind-set is dominant: Resources are limited. The world is dangerous. Group conflict is inevitable. It’s us versus them. If they win, we’re ruined, therefore, let’s stick with our tribe. The ends justify the means.

.. The scarcity mind-set is an acid that destroys every belief system it touches.

.. Now, Donald Trump leads the Republican Party, the personification of the scarcity mind-set. Fox News, with its daily gospel of resentments, is the most important organ of conservative opinion.

.. Republicans are happy to trade away their fiscal principles if they can get their way on immigration, which is what they did in last week’s budget deal.

.. He insists on perpetual warfare — against all comers. Stuck fighting his wars with him, Republican politicians have had to say goodbye to most of the pillars of conservatism:

• rule of law,
• fiscal discipline,
• global engagement,
• moral decency,
• the idea that people should be judged by the content of their character and not the color of their skin.

.. In theory, the G.O.P. restrictionist position on immigration is perfectly legitimate. But Trump has fatally entwined it with his constant race baiting. Republican politicians could have denounced the race baiting but remained silent. They allowed themselves to become fellow travelers to bigotry, and spoiled their own cause.

The fact is that the scarcity mentality and the perpetual warrior style it demands are incompatible with any civilized political creed. At first the warriors seem to be fighting for the creed but eventually they transform it.

Under the influence of this mentality, evangelicalism turns from a faith into a siege-mentality interest group that reveres a pagan immoralist. Under the influence of this mentality, liberalism goes from a creed that values individual rights and deliberation to one that values group separatism and intellectual intolerance.

The scarcity mentality always ends up eating the host philosophy because it operates on a more fundamental level of the psyche.

All of this would be survivable if the mentality was going away in a few years. But it is not going away. The underlying conditions of scarcity are only going to get worse. Moreover, the warrior mentality builds on itself. As the right pulverizes the left, the left feels the need to pulverize back, and on and on. This is a generational challenge. Trump will be succeeded by some other warrior.

Eventually, conservatives will realize: If we want to preserve conservatism, we can’t be in the same party as the clan warriors. Liberals will realize: If we want to preserve liberalism, we can’t be in the same party as the clan warriors.

Eventually, those who cherish the democratic way of life will realize they have to make a much more radical break than any they ever imagined. When this realization dawns the realignment begins. Even with all the structural barriers, we could end up with a European-style multiparty system.