Ask yourself if you’d still hold an opinion if you’d never seen anyone online argue about it.

Opinions get picked up by reaction as often as by thought. You see somebody obnoxious defending a position, and you find yourself holding the opposite one more firmly than the subject warrants. That is not reasoning, it is sorting yourself away from people you dislike.

Take one thing you believe strongly and ask what you would think if you had met it in a book, with no sides attached. Some of it will survive that and feel steadier. Some will turn out to be a reaction wearing the clothes of a conviction.