A performative contradiction is a statement whose effect goes against its intended meaning. A canonical example is Donald Trump’s January 6th tweet in which he insisted that he is a “very stable genius.”

Speaking last week about the President’s first physical exam in office, Ronny L. Jackson, the White House physician, stated that he “found no reason whatsoever to think the President has any issues whatsoever with his thought processes.” Trump had taken the Montreal Cognitive Assessment test for dementia and received a perfect score; the test typically takes ten minutes and asks subjects, for example, to identify pictures of a lion, camel, and rhinoceros; to state what a train and a bicycle have in common; and to recite “The cat always hid under the couch when dogs were in the room.” In the Times, Steven Buser—a former Air Force psychiatrist and a member of Duty to Warn, a movement of mental-health professionals who believe that Trump may be dangerously ill—wrote that he “certainly could not certify” Trump as ready to work with nuclear weapons “without more extensive psychological evaluation.” Buser and two other colleagues in Duty to Warn also wrote in USA Today that while Trump’s test score rules out full-blown dementia, it is “entirely compatible with significant cognitive decline.”

Questioning Trump’s mental capacity nourishes fantasies of ousting him from office via the Twenty-fifth Amendment. At the moment, it may seem the more likely route of removal, since the other path—impeachment in the House and conviction in the Senate for “treason, bribery, or other high crimes and misdemeanors”—seems like a foreclosed possibility so long as Republicans control Congress. The meaning of “high crimes and misdemeanors” for impeachment purposes is famously underspecified, and is not synonymous with “crimes” for purposes of ordinary criminal liability. (It is unlikely that a sitting President can be criminally indicted in court.) But many people hold out hope that, if the special counsel Robert Mueller’s investigation discloses a federal crime, that revelation may spur Congress to impeach Trump (though Congress need not wait for Mueller’s findings to do so).

There is a tension between these two paths. In the hypothetical scenario in which Trump’s mental impairment warranted invoking the Twenty-fifth Amendment, that same impairment might also render him incapable of having criminal intent.

In situations of “diminished capacity,” which could mean an abnormality such as dementia or a personality disorder, a person may be incapable of forming a mens rea, or “guilty mind”—the intention and understanding behind a crime. The federal case United States v. Brawner, from 1972, recognized the “diminished capacity” defense, and other courts since have also treated dementia, and even “mild cognitive impairment,” as relevant to a person’s competence to plead guilty, such as Alvarez-Jacinto v. United States, in 2010.

Mueller’s investigation likely focusses on obstruction of justice, which demands proof of corrupt intent; in that case, the remarkable public discourse around Trump’s mental unfitness would surely be helpful to the President’s legal counsel. If there is reasonable doubt as to whether Trump could have formed the mens rea to obstruct justice due to mental disease, or if he appears mentally incompetent to be tried or to plead guilty, then Congress may be even less willing to decide to impeach and convict him for high crimes. And, of course, Congress cannot impeach on grounds of mental incapacity.

This would not be the first time during the Trump Administration that Democrats faced a Catch-22 related to mens rea. Recent criminal-justice-reform efforts have included proposals to add a default mens rea element to all federal criminal statutes, which would require prosecutors to prove a defendant’s criminal intent—his purpose or knowledge at the time of the crime. Such proposals, which make convictions more difficult, address concerns common among liberals about over-criminalization and mass incarceration. But they also undermine enforcement of environmental and white-collar crime, favoring Trump’s corporate allies and anti-regulatory agenda—a likely reason for the Koch brothers’ support for such proposals.

It is altogether possible that Trump’s mental state is both one that is capable of criminal intent and one shaky enough that our potential nuclear annihilation should not depend on it. Trump may push against any narrative of mental impairment, but I wouldn’t count out the possibility that his lawyers will adopt one if it comes to that. Meanwhile, mental-health professionals who are trying to convince the public of Trump’s mental deterioration may be working at cross-purposes to the goal of impeachment or eventual criminal conviction. Paradoxically, fulfilling their “duty to warn” may be a step toward declaring the President not guilty.