Copied from elsewhere on the internet:
1. It’s the Internet, someone disagrees with you.
2. Not everyone who disagrees with you is obligated to be nice about it.
3. You may be a smart person, but that doesn’t always mean your opinions are well-informed or deserve to be taken seriously.
4. Not all opinions you disagree with are hateful or bigoted.
5. #4 Doesn’t necessarily mean your opinions *aren’t* hateful or bigoted.
6. Your freedom of speech doesn’t mean that no one is allowed to criticize, mock, or call you an asshole.
7. Your past hard work, sacrifices, good deeds, education, patriotic service, etc. doesn’t mean that no one gets to call you out for acting like a jerk or saying something dumb.
8. If you say you understand #6 and #7, but continue to cry “persecution!” or “double-standard!” or otherwise complain about “political correctness,” then you don’t really understand #6 and #7.
9. Just because a moderating organization or individual allows an opinion to be posted, it doesn’t mean they endorse, or even agree with, said opinion.
10. Don’t feel too bad if you’ve ever tripped-up on any of these: I just had to explain this to a group of PhDs.