There seems to remain a confusion of what types are actually sensing, intuiting, thinking and feeling. Let’s recap ISTPs are not sensing types, they’re thinking types. INTJs are not thinking types, they’re intuiting types, ENFPs are not feeling types they’re intuiting types as well. Remember Jung says:
Accurate investigation of the individual case consistently reveals the fact that, in conjunction with the dominant function, another function of secondary importance and therefore inferior in consciousness is constantly present and is a -- relatively determining factor.
Determining only in that my Se auxiliary function is what makes me distinctively different than INTP, INTJ from INFJ, ENFP from ENTP etc. But we are still ruled by the most differentiated function, which is dominant. Again Jung explains:
Absolute sovereignty always belongs, empirically, to one function alone, and can belong only to one function, because the equally independent intervention of another function would necessarily produce a different orientation which, partially at least, would contradict the first.
Here is a breakdown:
Thinking
Te – ENTJ/ESTJ
Ti – INTP/ISTP
Feeling
Fe – ENFJ/ESFJ
Fi – INFP/ISFP
Sensing
Se – ESTP/ESFP
Si – ISTJ/ISFJ
Intuiting
Ne – ENTP/ENFP
Ni – INTJ/INFJ
When ENTP/INTJs focus on their secondary function, they’re generally making claims that are exaggerated. For a highly extraverted ENTP, an equally high introverting ISFJ or INFJ may have better use of their Ti at the tertiary function. For INTJs with a high orientation to introversion a highly extraverted ENFP or ESFP may have better use of their Te.
The New York Association for Analytical Psychology defines Jung’s auxiliary function as “A helpful second or
third function, according to Jung's model of typology, that has a co-determining influence on consciousness.” Granted the third function cannot be the auxiliary since it does defy Jung’s principle that the secondary function must be different in all aspects than the dominant (i.e., dominant introverting and perceiving = auxiliary extraverting judging and vice-versa).