Nationalism, globalism, conservatism, liberalism, and neoconservatism are all legitimate philosophies that decent people can respectfully disagree on, even as smart public policy often resides in a compromise between all or some of those positions. But before a politician on the public stage can espouse any of the above philosophies in any form, he himself must be legitimate. Such legitimacy rests on being polite, well-spoken, respectful of others, a person of minimum good taste, and of course a role model, especially for young people. If he fails all of those criteria, as Donald Trump surely does, he has no right to be considered legitimate. That’s true even if some of his political positions speak to the legitimate concerns of much of the electorate.

It is one thing to say that Trump’s overall message finds resonance in the heartland and, therefore, must be addressed in some form. But it is quite another to say that Trump himself is therefore a serious candidate whom serious people should support. Trumps needy sense of dominance, his combination of aggression and narcissism, his very trashiness, means that any Republican who lines up behind him brings shame upon himself or herself.

This is because the President is not only the head of government in our system but the head of state. We do not have a Prime Minister with a monarch or Governor-General symbolically above him. Our system combines all functions. And, therefore, the primary function of a President—equal to his or her role as chief executive—is to maintain a sense of honor and dignity in all of his or her remarks and behavior in general. Presidents have failed at this at times. The history of the American presidency contains many poisonous examples of roguish behavior, even rare examples of outright criminality. But even those Presidents often felt shame afterward, and their general public behavior in office was still more-or-less decent. Trump, on the other hand—whether he is degrading women, immigrants, candidates’ wives, John McCain’s military service, and so forth; or referring to the size of a body part—constitutes a non-stop spectacle of vulgarity and semi-coherence fit only for the coliseum.

Within the past year I have traveled slowly across the country from one coast to the other, listening to people’s concerns. Trump, it is true, gives voice in his own brutal way to quite a few of them. People don’t want any more costly military interventions, they don’t want their jobs going overseas, they want a social safety net rather than a Darwinian economic system, even as they are uncomfortable with the so-called political correctness of elites. And many a reasonable candidate can speak to those concerns. But Trump is not a reasonable candidate. That is why sympathy for some or all of those views must be kept in a separate category from sympathy for Trump.

Without being a snob, I believe in minimal standards of behavior: for anyone, no less for a President. Trump does not meet those standards. He is not even close. That is why as a moderate conservative I will have no choice at this point but to vote for Hillary Clinton. I hope and believe there are millions of moderate conservatives like me.

A nation’s moral health is not only a matter of legality, or only its level of compassion for others, but of its very public style. And increasingly in this media age of ours the White House sets the tone regarding the state of that public style. American democracy survived and prospered in the print and typewriter age of the modern era. Donald Trump’s candidacy demonstrates that it might fare less well in this age of digital postmodernism. Decline is often associated with decadence. Decadence defines the person of Donald Trump.