But to be perfectly honest, I wouldn't even read such a thread. I saw lots of those threads over at INFP-gc when that message board was still alive, and those threads were devastatingly bad. They were one-sided and simplistic. Frankly, it's the things that are "mocking, hurtful, and cruel" that add depth and keep us honest.
Look, here's how I see these things:
If you really want an in-depth discussion of Fi, I think it's imperative to include all types. Fifty percent of all types are going to have at least some direct, personal experience of Fi, and that experience is going to vary widely depending on whether they're experiencing their own Fi as Dom, Aux, Tert, or Inferior. (I think the Inferior experience can be especially invaluable, since inferior functions almost have to be consciously re-fashioned in order to bring them under control; I'm disappointed that the other thread didn't have more ENTJ/ESTJ input.) The other fifty percent of all types are probably going to have some experience of Fi from the outside; i.e., they'll have family or friends or co-workers who are Fi-Dom or Fi-Aux. To some extent, these latter fifty percent are going to have the best input on what constitutes Fi on a general or universal level.
To the extent that Fi has some universal traits or features, the latter fifty percent (the non-Fi types) are going to be best positioned to identify those things. We Fi-Doms are not opaque, after all. We actually wear much more of our hearts on our sleeves than we like to admit. I've mentioned that my wife and I are both INFPs; I also worked in an INFP-heavy field (translation). As such, I see INFPs from the outside and I agree with the latter 50 percent when they say that we're much more identifiable, homogeneous, and predictable than we like to admit.
Yeah, there's going to be a lot of shouting in a thread open to all types. Some possessors of Fi are going to take a very personal approach and say, "I experience my Fi as such-and-such, so the description of Fi should be such-and-such too." Other personality types are going to get frustrated at that kind of personalization of an objective thing--a cognitive function--and they're going to raise a fuss about it. And they're right to do so. As I said, their job is to keep us honest.
My solution: I've found that the non-Fi types are generally willing to back off and give us some room to discuss things when asked politely. But in return, we have to keep the discussion "honest." IOW, I can't individually personalize the function and try to make the thread specifically about how I manifest my own Fi personally. The thread shouldn't be about me. If I try to make it about me, the non-Fi types are going to object. And naturally, my feelings are going to get hurt, since I've made the thread about ME.
To make a comparison:
It's like having a thread to define what constitutes "a good and complete definition of the female face." Other threads will be devoted to what constitutes "a good and complete definition of the male face" (in place of Fe), "...the female body" (Ni), "...the male body" (Ne), "...the female reproductive system" (Ti), and so on. You get the picture.
So in the thread what constitutes the female face, let's say we have invited women, men, medical doctors, artists, beauticians, plastic surgeons, movie actresses and actors, transgender people, etc. Some are going to speak from an insider's (woman's) point of view, and some are going to speak from an outsider's (man's) point of view. Issues of beauty and ugliness are going to come up; issues of political correctness and gender politics are going to come up. There will be questions of what constitutes "femininity"--is it a synonym for female appearance? And so on. But the discussion can probably handle all of that.
So what's going to kill the discussion? It's when one or maybe several individuals try to turn the debate into a discussion of their own face and how it specifically embodies femininity. Sure, sometimes an individual example is illuminating, especially one that breaks all the rules (as in "the exception that proves the rule"). Still, the discussion has to return back to universal rules pretty quickly, or people are going to start objecting. And frankly, you're setting yourself up for some cattiness if you try to insist that you yourself exemplify the ideal of feminine looks. Also, some of the participants have seen it all, and they're going to get a little irritated if the discussion hangs up too long on features that may seem unique and individual to one person but really aren't all that uncommon to people who have seen a lot of cases.
Okay, getting back to Fi: What happens when someone personalizes the discussion, tries to make the thread about themselves and their relationship with their Fi, and they are dismissed by the other participants? What happens when, for example, I speak up and the other participants say things to me that that are "mocking, hurtful, and cruel"? I feel ashamed, and I learn a lesson.
Frankly, I think shame is a wonderful thing. As I grow older, I come to have more and more respect for it, both in receiving it and doling it out. When I feel ashamed, it's a good reality check. It almost always means that I'm relying too hard on one cognitive function (in my case Fi, usually) and that it's time to engage another cognitive function. I've gotten too wrapped up in my own needs, and it's time to look around me and recognize the needs of the other people sharing the room or the thread.
In the case of those who personalize the subject matter to the point of making the thread "about them"--and then end up feeling ashamed when the point they are making is dismissed or rejected--the lesson is simple enough: You need to put your point in other language that the other participants will respect. Use a little Te and research the subject. Find some indication that the phenomenon exists outside the single example of you alone; back up your assertions with a citation from experts, or point out where the phenomenon is visibly manifested on the message board itself.
Or use your Te to compartmentalize: Learn to discuss Fi only in threads where NFs can post, i.e., where you can create your perfect audience, and stay out of threads for the entire population of 16 types.
In other words, don't let your Fi get injured; bring in another function (usually Te for Fi-Doms, though sometimes Fe is useful too) for support and reinforcement. Be realistic about what the situation demands if you really want to win your point. Remember the cardinal rule for performers: Know your audience.
To sum up: If you really do want an open, freewheeling discussion about Fi with some real depth, then you need to invite in other types. Fifty percent of all types are going to have at least some direct, personal experience of Fi, and the other fifty percent of all types are probably going to have some experience of Fi from the outside. But that's a lot of variety of experience. You aren't going to get a free pass with that crowd.
In a freewheeling discussion venue like this one, there's no harm in bringing up a personal observation of whatever nature. But by the same token, there's no harm when others dismiss it or even ridicule it. If you really think your point has validity, then be realistic about what the debate situation demands. Don't let your Fi get injured; bring in another function to counterbalance your Fi and put your argument in language the other participants will respect.
(Hey it's all pop psychology in the end. Gotta have a sense of humor about it. )