Again, the key to the Dunning-Kruger Effect is not that unknowledgeable voters are uninformed; it is that they are often misinformed—their heads filled with false data, facts and theories that can lead to misguided conclusions held with tenacious confidence and extreme partisanship, perhaps some that make them nod in agreement with Trump at his rallies.

Trump himself also exemplifies this exact pattern, showing how the Dunning-Kruger Effect can lead to what seems an indomitable sense of certainty. All it takes is not knowing the point at which the proper application of a sensible idea turns into malpractice.

For example, in a CNBC interview, Trump suggested that the U.S. government debt could easily be reduced by asking federal bondholders to “take a haircut,” agreeing to receive a little less than the bond’s full face value if the U.S. economy ran into trouble. In a sense, this is a sensible idea commonly applied—at least in business, where companies commonly renegotiate the terms of their debt.

But stretching it to governmental finance strains reason beyond acceptability. And in his suggestion, Trump illustrated not knowing the horror show of consequences his seemingly modest proposal would produce. For the U.S. government, his suggestion would produce no less than an unprecedented earthquake in world finance. It would represent the de facto default of the U.S. on its debt—and the U.S. government has paid its debt in full since the time of Alexander Hamilton. The certainty and safety imbued in U.S. Treasury bonds is the bedrock upon which much of world finance rests.