Washington — In the carnage of American civic culture, some of the damage is obvious: the dehumanization of political opponents, the devaluation of truth, the rise of conspiracy thinking. But other less evident shifts are no less troubling. One concerns the use of the word “authenticity.”

Most recently, we have seen the defense of vulgarity as authenticity. Rep. Rashida Tlaib, D-Mich., explained her use of the MF-word against President Trump as the expression of her “very passionate” nature. The same argument is more familiar from Trump defenders, who explain away his endless vulgarity and malice as quirks of an oversized personality. Isn’t it refreshing when politicians speak what is really on their mind?

In this view, humans are most genuine when we are least guarded, least scripted and least self-controlled. By this definition, we are most authentic while hitting our finger with a hammer, or after our third martinis, or maybe on a Twitter rampage.

Without intending it, Tlaib and Trump have wandered into an important moral debate. And not a new one. In any ethical system derived from Aristotle, human beings fulfill their nature by exercising their reason and habituating certain virtues, such as courage, temperance, honor, equanimity, truthfulness, justice and friendship. Authenticity — at least authenticity defined as congruence with your unformed self — is not on the list. In fact, this view of ethics requires a kind of virtuous hypocrisy — modeling ourselves on a moral example, until, through action and habit, we come to embody that ideal. Ethical development is, in a certain way, theatrical. We play the role of someone we admire until we become someone worthy of admiration.

But there is a rival tradition. In any ethical tradition derived from Jean-Jacques Rousseau, authenticity is at the apex of the virtues. This view starts from the premise that man is born free but is everywhere in social chains. Being true to yourself, and expressing yourself freely, is seen as the chief requirement of a meaningful and happy life. In this system, the worst sin is hypocrisy — being untrue to the real you.

This approach to ethics is also theatrical, but in a different way. In Rousseau’s view, we are performers as ourselves, and life is a kind of transgressive art form. Being true to ourselves means being true to our eccentricities. Especially to our eccentricities.

At the root of the Aristotelian approach is the premise that the human person is originally in need of formation. At the root of the other approach is the premise that the human person is only in need of liberation. This has marked a long-standing difference between right and left, with conservatism often on the side of character building and progressivism often on the side of personal expression. But with Trump, something remarkable has happened. The right is increasingly on Rousseau’s side as well.

This view of ethics is a perfect philosophic fit for the president’s narcissism. The soundtrack of his whole life has been Frank Sinatra crooning, “I did it my way.” And social media is the perfect platform for Rousseau’s view of authenticity and for Trump’s brand of performance art. After 2,500 years of debate and reflection, the highest human ideal turns out to be … reality television.

Here is the skunk at the orgy. If the unfiltered expression of self is the highest virtue, then the moral content of that expression becomes a secondary matter. Trump may be speaking lies, nonsense or racism, but he remains authentic. This form of ethics can act as a shield from responsibility. Most of us — not just Trump supporters — have learned to discount the content of Trump’s self-expression. We figure that is just his shtick. Just Trump being Trump. This way, Trump is seen as an authentic communicator, even when he lies — because the author of those lies is somehow true to himself.

I’m afraid I don’t see many Aristotelians responding: That is not the way a president should act. That is not the way a man should act. That is not the way a human being should act. This form of authenticity is just the refusal to master the self. It is really moral laziness, and cruelty, and deception, and decadence. And the repetition of these failures should not numb us. It should serve to reinforce our conviction that Trump is a man of bad character, unworthy of respect, unworthy of trust and unworthy of high office.

— Michael Gerson is a columnist for Washington Post Writers Group.