Think of it like Ti... if one has analyzed something in depth, then one is reasonably certain (sometimes to the point of dismissing information to the contrary at first). If it's an new kind of event/problem/situation, than one has less certainly and judgments are much more tentative. Fi, like Ti, is all about the nuances and depth of understanding, although Fi focuses more on meaning, emotion, ethics, etc. We tend to be very flexible about understanding the viewpoints of others and giving them a benefit of a doubt. The exception, at least for INFPs, is when a core value is perceived to have been violated, and then openness to subtlety and nuance can fly out the window.
Subjectively, I feel like I'm continually evaluating what's going one around me. There's a continuous, almost subliminal evaluation about what's good or bad, what's ideal or less-than-ideal, what's aesthetically better or worse.
When I hear INTPs talk about continually evaluating the logical correctness of things, it sounds parallel to the continual Feeling judgments I make. Emotions are valuable input to all that evaluation (and often represent a lot of unconscious judgment), but they are not themselves truth or Feeling evaluations.
We can tend to assume that others are moral and ethical free agents, responsible for their own actions. That being the case, we can be easy going until someone intrudes on our own ethical domain or treats someone else cruelly.
Hypocrisy, a near universal human trait, is certainly possible with Fi, since Fi tends to optimize for the particulars situation. Just as Te tends to be more about broad utility, while Ti is more about precision in a particular domain, so with Fe and Fi. Since every situation is unique, there exists a possibility of finding justification. This can lead to cases where a Fi dom or aux can discard the general accepted ethical stance, believing that THIS time no one will be hurt, or that there are extenuating circumstances or whatever. Hence, we can sometimes be blind to the long term ramifications of our actions in ways that NFJs, for example, are not. "I really MEANT well," no matter how true it may be, only covers so much.
On the other hand, we do tend to hold ourselves to high standards and judge ourselves pretty harshly. Plus, some of the more "universal concerns" (treating others with respect, etc) usually prevent us from going too far afield. That doesn't me we always live up to our values in practice, though.