So I asked a guy--and I forget his exact qualifications but he's been an MBTI Consultant for years, trains consultants and is a degree qualified neuropsychologist, and ENFP--and he said he favors Isabel's interpretation of Jung: that a person has (eventual access to) 4 cognitive functions and that the dominant has one orientation and the other three functions are oriented opposite to the dominant. So, if your dominant is e, all the others are i, and vice versa. So I asked him, how do you know? He said, I observed it. I asked, how did you observe it? He said, in lots of lengthy MBTI consults and debriefs.
Official MBTI position currently in discussing type dynamics is to leave the orientation of the tertiary unspecified. So I guess it's a real debate. Either that or the institution is just taking a while to officially change a position that had been held for fifty years.
But this guy said his observations supported the traditional model.
Yeah, I know this looks like an argument from authority, but what if his observations are real?
Free research project for someone: Enneagram variations and tertiary orientation.
Hypothesis: INTJ 5w4 have Fi as tertiary while INTJ 4's--or 8's or 1's or whatever--have Fe (and are trying not to implode).