The liar says he tells the truth and those who call his lies are liars. Greeks rhetoricians called this device the liar’s paradox.
The New York Times explicitly acknowledged the liar’s paradox in a recent headline, “New Press Aid Vowed Never to Lie. That Was the First Lie” (May 2, 2020, print edition p. A22). But the Times quickly got cold feet, revising the headline for the digital edition to “‘I Will Never Lie to You,’ McEnany Says in First White House Briefing: But Kayleigh McEnany, the president’s fourth press secretary, found that vow tested almost immediately.”