1. Attacking the person and not their argument.

I see this all the time, especially on Twitter. Every person's opinion is just as valid as your own. Don't weaken your argument by attacking the person when you could easily argue against their point.

2. Closing our ears to what other people think.

Every side to every argument has advantages and disadvantages. Don't act like your opinion is 100% correct in every way. It's not. There are things that you could learn from the other party's point of view, even if not their argument itself.

3. Hearing an argument once and then repeating it wherever we go.

Just because someone you trust and respect tells you that such-and-such fact about Donald Trump is true, doesn't mean that it actually is. So let's make sure we're checking other people's facts as well, and not simply repeating it because it lines up with what we believe.

4. Not citing our sources.

This isn't just in writing. It's classic ethos: using your credibility to strengthen your argument. Do it for that reason, at the very least. Citing your sources in verbal arguments is just as important as it is in writing.

5. Calling people "irrelevant."

Nobody is irrelevant, and everyone's opinion matters, even if it is not justified. It is hard to listen to people when they invalidate your opinions. If you want people to agree with you, then you are already saying that they matter. If they didn't matter, then you wouldn't care what they think; so just come right out and admit that they are valid and relevant, simply because they are human.