“In 1993, New York’s Democratic senator Daniel Patrick Moynihan, a former social scientist, made an incisive observation: Humans have a limited ability to cope with people behaving in ways that depart from shared standards. When unwritten rules are violated over and over, Moynihan observed, societies have a tendency to “define deviancy down” — to shift the standard. What was once seen as abnormal becomes normal.
“Moynihan applies this insight, controversially, to America’s growing social tolerance for single-parent families, high murder rates, and mental illness. Today it can be applied to American democracy. Although political deviance — the violation of unwritten rules of civility, of respect for the press, of not lying — did not originate with Donald Trump, his presidency is accelerating it. Under President Trump, America has been defining political deviancy down. The president’s routine use of personal insult, bullying, lying, and cheating has, inevitably, helped to normalize such practices. Trump’s tweets may trigger outrage from the media, Democrats, and some Republicans, but the effectiveness of their responses is limited by the sheer quantity of violations. As Moynihan observed, in the face of widespread deviance, we become overwhelmed — and the desensitized. We grow accustomed to what we previously thought to be scandalous.”
— Steven Levitsky and Daniel Ziblatt, “How Democracies Die”, 2018, (pp. 200-201)