When such methods of transcending tribalism fall short, one response is to advocate trying harder to do better. Another is to mock the effort and treat the ideals themselves as a sham. For much of our history we’ve defaulted to the first option. But now one of our two political parties is led by a man who’s unwaveringly committed to the second, and he’s backed up in his efforts by a right-wing media infrastructure that amplifies his efforts every day.

Without fully grasping the consequences of his words and deeds, President Trump has done more than any previous president to advance a politics of sophistry and cynicism. It’s a politics defined by the unrelenting effort to prove that every apparent act of virtue is in fact an example of something lower — of the very tribalism that motivates Trump’s every public utterance and act.

If all politics is zero-sum tribalism, then the president’s own zero-sum tribalism no longer seems quite so out of line. It can even seem normal. Which is no doubt one reason why he delights in tearing down the norms that call on us to put aside our self-interest, or to view our self-interest as reaching its ultimate fulfillment, in pursuit of the common good.