Prejudice and self-sufficiency naturally proceed from inexperience of the world and ignorance of mankind.

Certainty about whole groups of people is mostly a symptom of not having met many of them. The less experience somebody has, the tidier their picture of the world, because there is nothing in it yet to complicate the categories. The same shortage produces the belief that you need no one, which survives only until something arrives that you cannot handle alone. Both soften with exposure rather than with argument.

Rather than debating an opinion you suspect is narrow, put yourself somewhere that tests it. Spend real time with the people or the work you have been judging from a distance.