Guidelines for commenting in a field not your own

Quite a lot in online discussions I see otherwise highly intelligent people demonstrate a seemingly utter lack of ability to hold a civil argument.  I have been guilty of this myself.  So I thought about it for a while and came up with some guidelines for a civil discourse.

1. Don’t be arrogant.  Keep firmly in mind that maybe, just possibly, there’s a teensy-weensy chance that you aren’t the smartest person in the room.  This is especially so if you are an expert in one field commenting on an area that is not your field.  People with PhDs seem to have a particular problem with this.  Being an arrogant know-it-all will shut down the conversation and get you dismissed as an arrogant crank.  

2. Don’t shoot from the lip.  Keep firmly in mind that someone somewhere at some time for some reason thought the idea you’re commenting on was a good one.  If you start the discussion with words to the effect “That idea is insane and you’re stupid,” then that shuts down the conversation before it starts.  Approaching the subject with a little humility will yield far better results.  
First, instead of going on the attack, start by asking a question: “What leads you to believe this is a good idea?”  
Or lead an explanation.  “This idea doesn’t make sense to me, please explain it in more detail.”  
Or just ask questions, in a non-insulting manner, that make the people you’re disagreeing with justify their position.  
Instead of going on the attack turn the comment on yourself.  Instead of “you’re wrong” start with “I disagree”.  Then construct your argument accordingly.
You could construct your argument along these lines:
“As a [$CREDENTIAL] I think your idea is mistaken because [$FACTS], [$REASONING], [$CONCLUSIONS].  
Making a well reasoned argument will get you listened to.  Starting with insulting both ideas and people will get you dismissed as an arrogant crank.  

3. If you are commenting outside your field, and you think your field may add perspective to the conversation then say so.  Keep firmly in mind, however, that you are commenting outside your field.  When in doubt, see Guideline 1.  

4. Get the facts of the subject you’re commenting on before you comment.  Keep in mind that people in whatever forum you’re using may have facts you don’t, especially if they’ve been involved for a long time in a project that you’ve just stumbled across.  Get the facts before you comment, especially if you think an idea is a bad one.  If there are publicly available documents then get them, read them, and make sure you understand them before constructing your argument.  Spouting off before you have the facts, or refusing to learn them, will get you dismissed as an arrogant crank.  

5. Learn the language of the field in which you are commenting, especially if it is not your own, even if it is closely related to your own.  Every field has its own language.  Never assume the language is the same as your own field.   Even closely related fields may have significant differences in their nomenclature, terminology, concepts, and sources.  Learn them before you try to impose your will on a forum that is not in your field.  Failure to learn the language, and a refusal to do so, will get you dismissed as an arrogant crank.  

6. Learn something about the widely respected sources in the field in which you are commenting, especially if it is not your own field.  Most especially if you disagree with those sources.  Preferably before you insult them.  If you come out of the gate by insulting people’s mentors then the only thing you’re going to get is pushback, and dismissed as an arrogant crank.  

7. Keep in mind that unlettered people aren’t stupid.  An unlettered autodidact who spends a lot of time studying a subject of interest may, in fact, have knowledge that you don’t.  Insulting those people, their sources, their reasoning, their opinions, and their intelligence is not a good way to win friends or influence people, and will get you dismissed as an arrogant crank.  

8. When you’re an expert in one field who dabbles in another field as a hobby, and you find yourself in an argument with people who are credentialed working professionals in that field, then your best course of action is to listen to them before you disagree with them.  You, as a hobbyist, trying to dictate policy to working professionals in the field will not go over well.  As a hobbyist in a discussion with working professionals in a field, trying to explain their jobs to them, and refusing to listen to them, will get you dismissed as an arrogant crank.  

In conclusion, I think you get the idea by now.  Keeping a discussion civil is much more likely to get you listened to.  Even if you at first disagree strongly with an idea, make sure you wrap your mind around it fully before diving headfirst into disagreement.  Make sure you understand the facts, language, reasoning, and sources behind the idea before you vociferously disagree with it.  Just don’t be an arrogant crank and you won’t get dismissed as an arrogant crank.