I'm pasting this from an extended wall conversation I've been having with Two Point Two, because I thought it had some other applications and might result in some good discussion. It provides support for my ongoing assertion that only the four primary functions (dom, aux, tert, inf) are ever truly exercised.
This is in the context of speaking to an INTJ:
A good example of what I mean here is people who claim to be borderline P/J.
In actuality this doesn't make any sense because P and J imply completely different sets of functional value systems. I've seen people claim to be something like ENFx, which is ridiculous because it implies that Fi, Fe, Ni and Ne are all of equal importance to you, and this simply doesn't work because Fi and Fe are so fundamentally opposed in their approaches (same for Ni and Ne.) (Amusingly, people who claim ENFx are virtually always ENFPs who are just attracted to the idea of being "miscellaneous". "Wow, I don't fit into any of the molds! I guess that's cause I'm just SO unique and different!" It's no coincidence that "be unique and different/don't fit the molds/go outside the box" is such a huge part of Ne's value system. Go fucking figure!)
This is what I mean about how every behavior, thought, action and opinion can be reduced further until you end up with ~4 primary life directives...one for Je, one for Ji, one for Pe and one for Pi.
People who make these claims simply don't understand enough about functional dichotomies to recognize why they're implicitly contradicting themselves. We're not working with 8 mutually exclusive and completely independent processes here; we're working with an interconnected system of competing and often absolute opposite value systems. Saying that you value Fi and Fe equally is completely absurd; you just don't understand the implications of those terms.
I may "use Fi" sometimes, but not because I place any fundamental value in Fi itself, but rather because I recognize situations where Fi's values happen to align with my own (which are invariably the result of Ne+Ti+Fe+Si.) I have no shame in admitting that I find Ti a totally superior system for internal judgments, but then--of course I do, I'm a Ti user! Again you need to direct your focus toward the total reasoning process and its most basic underlying values, not just the surface behavior or end conclusion.
You as an Fi user may make decisions in some situations that resemble Fe decisions, but it's always possible to look further into the motivations for those decisions and recognize which function or functional combination was ultimately responsible. Just because you did something that a lot of Fe users commonly do doesn't mean that Fe actually motivated your reasoning process to do it. I realized this through just talking to a lot of people and prying for honest, deep insight as to the most basic values that make them tick--and trust me, nobody values Fi and Fe equally. The natures of those two value systems are too fundamentally contradictory.