I don't think this is true. You can disagree with a person without having to make every effort to signal they are evil. If you do this it just becomes group a v

I don't think this is true. You can disagree with a person without having to make every effort to signal they are evil. If you do this it just becomes group a vs group b. We like to form groups and defend our own instinctually. But our societies have grown in a way that means these instincts no longer help us but hinder us. Only when you find a way past that can you actually reason with a person.