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 shift in mentalities seems like a shift in philosophy. But it’s really a shift from a philosophy to an anti-philosophy. The scarcity mind-set is an acid that destroys every belief system it touches.

For example, in the years after Ronald Reagan, the Republican Party was defined by its abundance mind-set. The key Republican narratives were capitalist narratives about dynamic entrepreneurs and America’s heroic missions. The Wall Street Journal editorial page was the most important organ of conservative opinion. The party’s views on other issues, like immigration, were downstream from confidence in the abundant marketplace and the power of the American idea.

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. Restricting immigration has become the core Republican issue. Today’s 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.

The Trump era has produced a renaissance in conservative writing. National Review is a more interesting magazine now than at any time in its history. But the style of politics that Trump’s scarcity mind-set demands has been a disaster for conservative governance. 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.