According to Jung, the auxiliary function
C.G JUng said:
Its secondary importance consists in the fact that, in a
given case, it is not valid in its own right, as is the
primary function, as an absolutely reliable and decisive
factor, but comes into play more as an auxiliary or
complementary function.
And
C.G Jung Psychological Types Ch X page 515 said:
Hence the
auxiliary function is possible and useful only in so far
as it serves the leading function, without making any claim
to the autonomy of its own principle.
I bold what i think is important phrase in understanding the aux function. It is not valid in its own right and is not autonomous with its own principles.
I would like to elaborate what I think by this further. Any nature characteristics of each function theorized by Jung in Chapter X doesn't appear as it was explained if the function is positioned as an auxiliary function. When Rational functions (Te, Ti, Fe, Fi) for example is positioned in the auxiliary like Fi Aux (ESFP, ENFP), Te Aux (ISTJ, INTJ), Fe aux (ISFJ, INFJ), Ti Aux (ENTP, ESTP), the function will not behave as its nature as when it is positioned in primary Fi Primary (INFP, ISFP), Te Primary (ENTJ, ESTJ), Fe Primary (ESFJ, ENFJ), Ti primary (ISTP, INTP). I myself feel different with my father whom I type ENTJ. He reason much more frequent than I do , who identify myself as Te aux, and I identify his reasoning is objective, and frequently express if - then statement , and instruction to his outside world. Te function in my stack doesn't behave as its nature as in ENTJ. But, on the feeling side, frequently my mother judges my father doesn't have feeling nor does my sister (ISTP) or insensitive [may be to her feeling]. Sometimes my mother (ESFJ) even said that both of them don't have feeling, as far as I remember. Interestingly my mother never said it to me. I get a sense from her judgements that My feeling is more sensitive than both of my father (ENTJ) and my sister (ISTP). May be because of their feeling is located both as their inferior stack, and mine is at third stack, my mother seems to be able to sense that I am more feely than both of my father (ENTJ) and my sister (ISTP).
Important for who is interested to study the function further not from Literature; but directly from the person
This is also important for those who is interested in studying psychological Function further. To understand better Extroverted thinking function, but want to study from the function bearer, the student should find type with Te primary, like ENTJ or ESTJ, For Fe, we should find ESFJ, and ENFJ, for Fi, we should find INFP, ISFP, for Ti, we should find INTP, ISTP, since in their function stack, those function is valid in its own right and is autonomous with its own principles , like they -the rational functions-will behave rationally, expressing reason (because bla bla bla, ...), inquiring for a reason (s) by asking why, making conditional statement (If-Then), some justification, etc. The same reason applies also to irrational perceptive functions (Ne, Si, Se, Ni). To study the Ni, we should find INFJ, INTJ. To sudy the Si, we should find ISFJ, ISTJ. To study the Se, we should find ESTP, ESFP, to study the Ne, we should find ENTP, ENFP.
Based on this also that the secondary function is not autonomous with its own principles, and not valid for its own right, My casual method to identify which psychological functions serves as primary is more or less by examining verbal speech or written word, and try find out their reasoning first. Some tips to find reasoning is to find (when reading, scan) these words : "because" or "since", "why", "therefore"," hence", "so"," as a consequence", "If-Then statement", "thus", etc. When I notice that the person habitually use them in their expression, I can tell that their primary function is identified as a rational judging one (Te, Fi, Ti, Fe).
I even has a devise a crazy plan to record day by day verbal speech of three of my families and identify their reasoning. e.g a couple of days ago my mother said:
My mother said:
why God was so cruel to me?
. She said that after receiving a news that my sister did not pass a civil servant administrative screening. The expression is a reasoning, (she express Why), but fallacious (complex question), since in her question, there was an unquestioned assumption: God is cruel to her.