In addition to clinical diagnoses, such as narcissistic personality and delusional disorder, public commentators frequently dispense political diagnoses of President Trump. The most common are authoritarian, fascist, autocrat, dictator, totalitarian and demagogue. But only one of these, demagogue, is in fact accurate.

This distinction matters hugely at this juncture in our history, less than three weeks from a volatile presidential election, because if we have any hope of arresting our constitutional democracy’s descent into chaos and breakdown, we must first know exactly what struck us in the fateful year 2016.

The terms fascist, authoritarian and the other labels often attached to Trump are incorrect because they do not apply to the early or middle stages of the deterioration of a constitutional democracy; they apply to the end stages. Today we are not at the end stage of our democracy. We are instead at an early crossroads where a full-blown demagogue has ascended to the White House.

Trump’s election to the presidency has exposed the single greatest vulnerability –– and most destructive force –– present in a democracy. Aristotle breathlessly warned about it. So did Plato, Thucydides, Polybius, Livy, Edward Gibbon, Alexis de Tocqueville, the founders of the United States and Abraham Lincoln.

These statesmen and political philosophers uniformly exhorted the guardians of democracy to beware demagogues. In their writings and speeches, they elaborate a golden rule of this free yet fragile form of government: that the citizens of a democracy must work together tirelessly, irrespective of political and party differences, to keep demagogues out of high office.