Greetings y'all. I'm quite a newcomer to the forum, although I've been lurking around for a while now; appologies if this has been posted before (it probably has, but couldn't find anything).
Can someone shed some light or point me at some reading material on why (not how) dichotomies translate into cognitive functions and viceversa? I can sort of understand how the 4 dichotomies work, and how cognitive functions apply to people, but the relationship between them doesn't seem consistent.
I, myself, coming out of the closet as an intj with a weaker or stronger i can relate to Ni, Te, Ti, I see how Fi, Se, Ne, and Si play their fairly minor roles in my life, and would also gladly ship most strong Fe's and Se's around me (including my EnFj gf, who is the living incarnation of Fe on Earth) to an orbital reeducation camp. So I can at least see how the dominant and secondary stand out sometimes in people.
But given that the correlation between one's personality matrix and their actual behavior is rather weak (.3 - .4 maybe, according to some studies) and that when it comes to empyrical psychology we could agree that "natura non facit saltus" it's somewhat hard for me to understand how one change in the 4 dichotomies (I'm going to say from a P to a J) changes one's cognitive functions almost completely. Consistent manifestation of tertiaries or shadows seems highly unlikely from this perspective - how on Earth can someone pin a tertiary to you, if your primary and secondaries are barely visible with .3 certainty. Also, the algorithms by which cognitive functions are derived from dichotomies or viceversa seem akin to horoscopes (things like "if you have a J than your whatever function is extrovertite" on websites make my skin curdle).
It's a bit hard for me to formulate my questions exactly, so I'm hoping that someone can gather what my MBTI insecurities are from the above.