The late New York Times columnist William Safire famously called Hillary Clinton a “congenital liar.”  Others have called her a “pathological” liar.  Maybe what really ails her is what two researchers are calling “unethical amnesia.”

Maryam Kouchaki of Northwestern University and Francesca Gino of Harvard describe this phenomenon as a defense mechanism that helps our minds by “forgetting about the times we’ve acted unethically.”  In other words, when we cheat, lie, and act in other dishonest ways, our minds try to erase that behavior from our memories in order to protect ourselves from ourselves.

Blocking out the truth makes people prone to believe their own lies.  Were it not for the video proving otherwise, Clinton might still be telling the story of her courage in the face of heavy sniper fire on a tarmac in Bosnia.

Over nearly three decades of public life, Hillary Clinton’s lies have been numerous and varied.  A veritable cottage industry has sprung up documenting them, not only from conservative sources.

Long before she lied about Colin Powell advising her to use private email for State Department business, about having only one mobile device, and about turning over all her email, Hillary Clinton was a prolific teller of tales.  From suspicious profits garnered through cattle trades to the whereabouts of missing records to defending her husband’s lies with lies of her own, the range of prevarication is vast.

But ethical amnesia makes remembering lies difficult.  A decade ago she accused U.S. generals of lying about Iraq, calling for “a willing suspension of disbelief” when General David Petraeus spoke, and at least tacitly endorsed MoveOn.org’s “General Betray Us” advertisement.  But ethical amnesia kicked in on September 8, when she berated Donald Trump for “trash-talking American generals.”

Clinton’s amnesia concerning the Libya policy she oversaw is an acute case.  At first she took credit for toppling Moammar Gaddafi.  A 2011 interview on CBS was interrupted when Huma Abedin walked in and handed Clinton a BlackBerry (one of her 13 mobile devices, contrary to the lie she told about having only one).  Learning that Gaddafi was dead, she engaged in some impromptu Julius Caesar pilfering: “We came.  We saw.  He died.”  It was an odd moment of triumphalism she would soon forget while portraying herself as a back-seat player in the ever worsening Libya situation.

Her Libyan lies began when she said the Benghazi attack was a spontaneous protest over an obscure YouTube video.  She repeated that lie to the parents of those killed.  And then she lied again by implying that those parents were lying.

Recently, defending the Libya mission, Clinton actually asserted that “we did not lose a single American in that action.”  What else but ethical amnesia could cause her to forget her friend Christopher Stevens, and Sean Smith, Glen Doherty, and Tyrone Woods, the three men who died protecting him?

Bill Clinton seems to have a touch of his wife’s disease, too.  Recently he chided Trump for using the phrase “Make America Great Again.”  The former president, a white Southerner, revealed his own thoughts when he said: “If you’re a white Southerner, you know exactly what it means, don’t you?”  Was it the fog of unethical amnesia that caused him to forget the many times he used the slogan, both while running for president in 1991 and 1992 and while campaigning for his wife in 2008?

Kouchaki’s and Gino’s research suggests that as people get away with behavior others are punished for, their memories of that behavior fade.  Predictably, those “given latitude” to violate ethical standards are more likely to do so than those who are not.  Has anyone in modern political history been given more ethical latitude than the Clintons?

Hillary Clinton’s gravest unethical act is selling access to the office of secretary of state for personal gain.  Creating a way to hide that dishonesty, via her private server, came next.  Her lies about the whole arrangement cannot end so long as she seeks public office.  The more lies she gets away with, the more she forgets the truth and believes her own lies.

Whether she’s a congenital or pathological liar, or suffering from unethical amnesia, Hillary Clinton will surely continue to lie if elected president of the United States.