This is a question that I had wondered awhile ago but was reminded of it again by someone bringing it up recently in this thread.
In looking at a bunch of old threads, I noticed that there were several people (all dom/aux/tert Fi-users) independently saying that Fi (or Fi/Ne) was like Ni. Because several people are saying this, there must be something there. But I'm not understanding it. They have similarities that all introverted functions have, but I don't see it beyond that.
My concept of Fi is that it has to do with the personal values and feelings of the person using it, and that it identifies what values are at play in a given situation.
Ni on the other hand has nothing to do with values or feelings, and is as impersonal as a computer spitting out data.
So I'm obviously lacking in some understanding of what Fi is.
What do you think about this? What am I missing about what Fi is? Does anyone have any theories about how Ni and Fi (or Fi/Ne) are similar? Or how they work differently?