Personally, using abortion as an example because it does seem rather polarizing, I used to be anti, thanks to religious up-bringing. Once I lost religiosity, I had no external frame so I became ambivalent (it might be right in some cases, wrong in others). Now I would say I'm pro-choice, because I don't feel wrong about the idea in general. So perhaps that is an Fi-based judgment.
I guess my prevailing assumption has been that I have feelings, but do not know them. Is it valid to say, because I did action X I must feel this way? This seems like using Ti again.
Another thread asked if there were any beliefs you would die for (trying to get at someone's core beliefs). Of course, one of my favorite quotes for years was Russell's "I would never die for my beliefs, because I might be wrong"
Part of my fear of Fi judgments is because (perhaps this is P nature) I am concerned that they are either fickle, or ill-judged. I like person A one minute, the next I don't. I want this outcome, wait, no I don't.