The monolinguals are monolinguals. Some of the people in the United States have never even tried learning the language of their own nation, such as Spanish.
The root cause of the political divide can be cultural, religious, and at times, language issues. By learning languages, you'd immediately realize the limitation of one's own thinking.
You'd never come up with certain things in a particular language. If you call prudence some form of cowardice, you'd never learn humility.
The ignorant are the most arrogant. Judging the ability of a person in the field that you have never tried is just absurd.
“The limits of my languages means the limits of my world.” – Ludwig Wittgenstein
“He who knows no foreign languages knows nothing of his own.” – Johann Wolfgang
“Knowledge of languages is the doorway to wisdom.” – Roger Bacon