To succeed in the world, it is not enough to be stupid, you must also be well-mannered.                                                      —Voltaire

Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity.

 —Martin Luther King, Jr

Ordinarily he was insane, but he had lucid moments when he was merely stupid.

—Heinrich Heine

Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it.

 —Stephen Vizinczey

At least two-thirds of our miseries spring from human stupidity, human malice, and those great motivators and justifiers of malice and stupidity, idealism, dogmatism, and proselytizing zeal on behalf of religious or political idols.

 —Aldous Huxley

Most people would die sooner than think; in fact, they do.

—Bertrand Russell

The dumbest people I know are those who know it all.

 —Malcolm Forbes

It’s so simple to be wise. Just think of something stupid to say and say the opposite.

 —Sam Levenson

Just think how stupid the average person is, and then realize that half of them are even stupider.

 —George Carlin

Egotism is the anesthetic that dulls the pain of stupidity.

 —Frank Leahy

In view of the fact that God limited the intelligence of man, it seems unfair that he did not also limit his stupidity.

 —Konrad Adenauer

Most fools think they are only ignorant.

—Benjamin Franklin

Every creative act is a sudden cessation of stupidity.

 —Edward Herbert Land

If you say something stupid and no one disagrees, then you know that you’re the boss.

 —Phillip Simborg

If you attack stupidity, you attack an entrenched interest with friends in government and every walk of public life.

—Robertson Davies