Allen Frances is a psychiatrist who wrote the rules for diagnosing personality disorders in the Diagnostic and Statistical Manual of Mental Disorders. The DSM is the No. 1 tool mental health professionals have for making diagnoses.

Frances, a professor emeritus at Duke, doesn’t mince words about what he thinks of mental health professionals who are now using the DSM to diagnose President Donald Trump with a mental disorder. “What’s going on is bullshit,” he says.

Some mental health experts believe Trump has a severe mental disorder

Frances is talking about the recent Change.org petition — now signed by more than 20,000 people — headlined “Mental Health Professionals Declare Trump Is Mentally Ill And Must Be Removed.” But it’s also an ongoing discussion: Ever since the primaries, mental health professionals have been weighing in on Trump’s psychology — in Atlantic cover stories, in Vanity Fair, and on Twitter. It’s become something of a parlor game.

The Change.org petition strikes a louder note than many of these pieces. It’s not just saying Trump exhibits the personality trait of narcissism but also that he has a “serious mental illness.” The petition was started by John Gartner, a clinical psychologist and former Johns Hopkins professor. He’s convinced Trump suffers from an array of personality disorders, including narcissistic personality disorder, that makes him unfit for office and a danger to the world. “I would bet my life of my children on it [the diagnosis],” Gartner says. “That’s how confident I am.”

If you go down the list of diagnosing criteria for the disorder — which include things like “has a grandiose sense of self-importance” and “requires excessive admiration” — it does sound a lot like Donald Trump. But it’s not necessarily so simple.

Is it an illness if there’s no self-harm?

What’s missing in Gartner’s diagnosis, according to Frances, is the key element to diagnosing all mental illness: suffering.

“Everyone has a personality,” Frances says. “It’s not wrong to have a personality; it’s not mentally ill to have a personality. It’s only a disorder when it causes extreme distress, suffering, and impairment.”

Trump’s willingness to lie and endless self-promotion are traits that have, so far, worked out largely to his advantage. He’s president of the United States, after all.

But people who have a true narcissistic personality disorder, Frances explains, experience a crash of some sort, even if they can’t see it for themselves. They’ll lose their jobs, their spouses and children will abandon them, and their “bubble of grandiosity [will] burst,” he says. “They feel absolutely miserable, can’t function, can’t face the world.” (Research has found that a narcissistic personality can, to an extent, help you move up in the world.)

The American Psychiatric Association has a longstanding taboo on evaluating public figures from afar. It’s called the Goldwater Rule, named after an infamous magazine article in which politician Barry Goldwater’s psychological stability was assessed by thousands of psychiatrists. The rule forbids psychiatrists, who are medical doctors, from making judgments about a public figure’s mental health without personally evaluating them.

But the temptation to break it is always strong in presidential election years. The APA issued a warning to its members this past August, reminding them that “breaking the Goldwater Rule is irresponsible, potentially stigmatizing, and definitely unethical.” (Some in the psychiatric community believe the rule unproductively limits doctors’ free speech.)

Psychologists don’t have such a rule, and Frances — who supports the Goldwater Rule and generally thinks mental illnesses are overdiagnosed — worries that when the petitioners and others call Trump mentally ill, they stigmatize people with psychological problems. They can also distract from the more objective criticisms you can make of his presidency. “Call him a liar, call him evil, call him a threat to democracy, call him impulsive, call him ignorant — these labels are all absolutely true — but saying he has a mental disorder doesn’t really add force to the argument,” Frances says.

Gartner — who has a PhD and treats patients in a private practice — wholeheartedly disagrees with Frances’s position. “The thing about people with personality disorders … they don’t have distress related to their disorder; they cause distress in other people,” he says. “They’re in complete denial about the nature of their illness or even having an illness.”

Gartner feels like he has a “duty to warn” the country about Trump’s potentially pathological behavior. “The duty to warn someone who might be a potential victim of violence trumps — pun intended — all other ethical requirements,” he says. “We often make diagnoses through the reports of informants.”

And in Trump’s case, he says there’s no better source than the public record to prove he is ill. Gartner points out:

Trump’s inability to let go of perceived slights, like the time he publicly attacked the Muslim parents of a fallen soldier

His willingness to exploit the weak in the case of Trump University, which sold individuals on the promise that they could become self-starting real estate entrepreneurs with just a few (very expensive) classes

His leaked comments bragging to Billy Bush about sexual assault and his lack of remorse

His “irritability and aggressiveness” (another diagnostic criterion for personality disorders), like his reportedly hostile conversation with the prime minister of Australia

Gartner says he doesn’t need to sit down with Trump to recognize this is a dangerous pattern of behavior.

I asked Gartner if it’s possible he’s engaging in some motivated reasoning. That because he dislikes Trump’s politics, he’s looking for the signs of mental illness while discounting complicating factors. He denied it. “I didn’t like George W. Bush, and I bitched and moaned all through his presidency, but I didn’t think he was crazy,” he says. When I asked whether he could imagine a Republican psychologist coming to a different conclusion from him. After all, there are many in this country who like Donald Trump, and are approving of his job performance so far. He said, “I’m sure that’s possible.”

But “as someone who has been an expert and a teacher of severe personality disorders in 35 years, this is the worst case I have seen in my career,” he says.

The truth is the line between strong personality and mental illness isn’t always clear — even for the experts

So who’s right here? Gartner or Frances?

I called Joshua Miller, a psychologist who directs the University of Georgia’s clinical training program and studies the differences between personality and disorder, for a third perspective. He says that in many cases, it can be hard to tell where personality ends and illness begins.

That’s because these days, most mental illnesses exist on a spectrum. “Even disorders we thought ... you either had it or not — categorical things like schizophrenia — we now know are much more like spectrum disorders,” he says. “You can have some schizophrenic traits, but not all.” And that’s especially true of personality disorders, which he says are all just extreme manifestations of otherwise “normal” personality traits.

The question What is a mental disorder? he says is “probably one of the most intractable debates that exists. And it’s playing out with Trump now.”

The DSM is meant to standardize treatment and care of mental illness. It’s meant to decrease the subjectivity of making a diagnosis. And it’s the best tool the profession has.

But the human brain avoids standardization. The truth is, Miller says, “there is no magical point where you go from having sub-threshold narcissism to a disorder. We can make a cutoff, but we should acknowledge it is arbitrary. ... There is no sharp divide between ... a shitty personality and a disorder.” All of our personalities cause us and others harm every now and then. It takes an extremely clear and consistent pattern of harm to reach the level of a diagnosis.

Many people make bad or immoral decisions and do not suffer from any malady. As psychologist Cedar Riener wrote for Vox, calling Trump’s behavior an illness may be an easy escape from answering hard questions about politics today:

Efforts to label Trump with a mental disorder let us off the hook in thinking about the kinds of personalities our culture rewards — and about the state of our politics. The very traits that many claim are toxic and dysfunctional have not only failed to harm him but have contributed to his success.

Perhaps elites are particularly concerned about Trump’s stability because he does not act, talk, or think like them. More information would help a diagnosis. Though Trump has a long public record of worrisome behavior, these episodes still represent thin slices of his life.

Trump has a personal life, relationships with children and grandchildren, that’s obscured from view. What other narrative about his mental health would those relationships reveal? “You always want collateral information,” Miller says. “If I was seeing a patient for anything, I would want to talk to their spouse or children, if possible. ... You might get more nuanced information.”

At the New York Times, psychiatrist Richard Friedman explains that a comprehensive clinical screening could pick up on other problems causing the narcissistic behavior — like attention deficit hyperactivity disorder or bipolar disorder.

Because of the incomplete picture — and because of the damaging potential to stigmatize mental illness or, worse, make the field of psychology a partisan piñata — I’m more convinced by Frances’s point of view. A case against Trump should be grounded in his visible actions, which are clear enough, and not in the ultimately unknowable configuration of his mind.

And even if Trump’s behavior is purely the result of his personality, that’s still consequential. Psychologists generally feel personality is a stable trait. And that means our past behavior predicts our future behavior. What’s more, research finds ascending the ladder of power only magnifies your personality traits, and makes you more likely to act in accordance with them. You don’t need a diagnosis to say Trump has a troubling pattern of behavior or conclude that pattern is bound to continually repeat.

I asked Frances if he could rewrite his diagnostic guide in the DSM, what changes he would make. “I would have put in a clearer injunction against using the diagnosis in any situation other than the office setting,” he says. “For the 5 percent of the population who have a severe mental disorder, the boundary is absolutely clear-cut, but [with] many people who have mild to moderate psychiatric problems, the boundary with normality is extremely fuzzy, and moving. That’s why it’s always wise to be cautious and underdiagnose.”