"Stupidity is a more dangerous enemy of the good than malice. One may protest against evil; it can be exposed and, if need be, prevented by use of force. Evil always carries within itself the germ of its own subversion in that it leaves behind in human beings at least a sense of unease. Against stupidity we are defenseless. Neither protests nor the use of force accomplish anything here; reasons fall on deaf ears; facts that contradict one’s prejudgment simply need not be believed- in such moments the stupid person even becomes critical – and when facts are irrefutable they are just pushed aside as inconsequential, as incidental. In all this the stupid person, in contrast to the malicious one, is utterly self-satisfied and, being easily irritated, becomes dangerous by going on the attack. For that reason, greater caution is called for than with a malicious one. Never again will we try to persuade the stupid person with reasons, for it is senseless and dangerous.
If we want to know how to get the better of stupidity, we must seek to understand its nature. This much is certain, that it is in essence not an intellectual defect but a human one. There are human beings who are of remarkably agile intellect yet stupid, and others who are intellectually quite dull yet anything but stupid. We discover this to our surprise in particular situations. The impression one gains is not so much that stupidity is a congenital defect, but that, under certain circumstances, people are made stupid or that they allow this to happen to them. We note further that people who have isolated themselves from others or who live in solitude manifest this defect less frequently than individuals or groups of people inclined or condemned to sociability. And so it would seem that stupidity is perhaps less a psychological than a sociological problem. It is a particular form of the impact of historical circumstances on human beings, a psychological concomitant of certain external conditions. Upon closer observation, it becomes apparent that every strong upsurge of power in the public sphere, be it of a political or of a religious nature, infects a large part of humankind with stupidity. It would even seem that this is virtually a sociological-psychological law. The power of the one needs the stupidity of the other.The process at work here is not that particular human capacities, for instance, the intellect, suddenly atrophy or fail. Instead, it seems that under the overwhelming impact of rising power, humans are deprived of their inner independence, and, more or less consciously, give up establishing an autonomous position toward the emerging circumstances. The fact that the stupid person is often stubborn must not blind us to the fact that he is not independent. In conversation with him, one virtually feels that one is dealing not at all with a person, but with slogans, catchwords and the like that have taken possession of him. He is under a spell, blinded, misused, and abused in his very being. Having thus become a mindless tool, the stupid person will also be capable of any evil and at the same time incapable of seeing that it is evil. This is where the danger of diabolical misuse lurks, for it is this that can once and for all destroy human beings."
-Dietrich Bonhoeffer, from ‘On Stupidity’ (Letters and Papers from Prison)