I'd say Jung's model for a Ti-dom with an N aux is best viewed as either Ti-Ni-Se-Fe or Ti-N-Se-Fe. And the best argument for leaving out the attitude for the auxiliary is that Jung thought the auxiliary, because it "served" the dominant function, wasn't "autonomous" or "true to its own principle" to the same extent as when it was the dominant function.
Originally Posted by Eric B
The only two things I want to add at this point are:
1. To maybe clarify, when I talk about what I think Jung's view of the functions was, I'm not saying that's my view. I don't really view MBTI type from a functions perspective at all.
2. As for "the people whose types seem to fit a dominant with an opposite attitude auxiliary," I'd say it's important to keep in mind that the cognitive functions descriptions you find in modern theorists like Thomson, Berens and Nardi are different — sometimes in substantial respects — from Jung's descriptions, and in most cases the revised versions of the functions are substantially jerry-rigged to match the MBTI types to which (under Myers' model) they purportedly correspond. If what you're talking about is Jung's function descriptions, they very often don't fit. For example, Jung's Fe description emphasizes that Fe tends to adopt the community values of the person's time and place, and it's emphatically non-Jungian to expect that to apply to any introvert — including an I_FJ who purportedly has Fe as their auxiliary function — since Jung said it was characteristic of all the extraverted types to adopt majority values and characteristic of all introverted types to tend to shun majority values. As Jung explained (describing extraverts and introverts generally):
[W]e shall come upon individuals who in all their judgments, perceptions, feelings, affects, and actions feel external factors to be the predominant motivating force, or who at least give weight to them no matter whether causal or final motives are in question. I will give some examples of what I mean. St. Augustine: "I would not believe the Gospel if the authority of the Catholic Church did not compel it." ... One man finds a piece of modern music beautiful because everybody else pretends it is beautiful. Another marries in order to please his parents but very much against his own interests. ... There are not a few who in everything they do or don't do have but one motive in mind: what will others think of them? "One need not be ashamed of a thing if nobody knows about it."
[The previous examples] point to a psychological peculiarity that can be sharply distinguished from another attitude which, by contrast, is motivated chiefly by internal or subjective factors. A person of this type might say: "I know I could give my father the greatest pleasure if I did so and so, but I don't happen to think that way." ... There are some who feel happy only when they are quite sure nobody knows about it, and to them a thing is disagreeable just because it is pleasing to everyone else. They seek the good where no one would think of finding it. ... Such a person would have replied to St. Augustine: "I would believe the Gospel if the authority of the Catholic Church did not compel it." Always he has to prove that everything he does rests on his own decisions and convictions, and never because he is influenced by anyone, or desires to please or conciliate some person or opinion.