Good stuff.
With regards to the bolded:
- Could you clarify what you mean by "validation"?
Psychological validation, the stuff that makes people feel good about themselves and what they're doing. The carrot at the end of the stick that we all want--whatever it is that makes us feel valuable, productive and self-actualized.
- I'm assuming that objective and subjective here are not highly related to the ideas of accuracy, no? More about world vs self, right?
Yes. I'm using those terms in their most literal sense, as in, originating from the subject (self) or object (not-self.)
With regards to personality disorders:
- Do you think this is really where they stem from? Or do you think they have other origins?
Both. I'm not any sort of authority on personality disorders so I can't make any kind of claim that this is the only reason they happen. I doubt that Jungian functions paint a complete picture of human psychology so I'm sure there are other causes, but I think this is probably one possible cause (or at least, a description of the effects of personality disorders in Jungian functional terms.)
- If the former, do you think there are other functional relations that can also explain them, or just the ones you mentioned?
I can't recall having seen any in practice, but there may exist even weirder functional combinations that produce even worse imbalances. Like if you depended primarily on dominant+inferior, that might explain extreme indecisiveness/inability to follow through with anything (if the two functions used are perceiving) or extreme stubbornness (if the two functions used are judging.)
- If the former, what are they? How about the other personality disorders?
Well, if you look at each personality disorder and each of the 16 dom+tert loops you can find a lot of correlations.
INTPs using Ti+Si can get stuck in antisocial/schizotypal sorts of disorders because Ti reasons that social interaction is completely illogical and unpredictable, and Si remembers every previous attempt at social integration having failed, so the INTP doesn't see any reason to try. When you introduce much-needed Ne, he finds the will to try new approaches and experiment in real time until he finally finds something that creates a new result.
Another interesting effect is that each type in its dom/tert loop starts to look like the type that only shares its first letter, in its own dom/tert loop. For instance, little linguist (an ENFP in Ne+Te mode) spent a really long time trying to get others to figure out her type. She described marked difficulty with considering her own subjective perspective and noted that she was very dependent on the opinions of others, to the point of making her uncomfortable.
She rejected ENFP labeling at first, and my next guess was actually ESTJ, because its dom+tert loop is Te+Ne...which looks rather like the ENFP's Ne+Te. (Similarly, I've come to the conclusion that Victor is either ISFP or INTJ in a dom/tert loop because his posts are almost entirely Ni+Fi...or Fi+Ni.)
Oh, and the real $40 million question:
- If, for example, an INTJ believes he uses both Ti and Ne in relative abundance (as in, equal to or greater than his tertiary function), then what of the relationship(s) between Ni and Ti and Ne and Te...
- Also, necessarily unhealthy and unproductive? Or potentially healthy and productive?
My opinion on this isn't very popular, but if you want to know what I really think, I doubt that this INTJ genuinely uses Ne or Ti very often, because using a shadow function requires temporarily breaking out of one's preferred perspective...which tends to require an unusual set of circumstances that forces us into uncomfortable psychological territory.
I'd say it's more likely that this INTJ has simply figured out how to do a lot of things that Ne/Ti-ers do well, but using Ni/Te instead. I think a lot of people assume incorrectly that functions equate with particular skills; e.g., finding a pattern means "using Ne" or whatnot, but I don't agree with that. I think Ne and Ti represent types of perspectives, not so much individual skills...how did you reason that you're using Ne and Ti frequently? Is it because you find that you're proficient in many skills that Ne/Ti people are usually good at?
I would argue that, while this may be true, it doesn't necessarily imply use of those functions, because you can easily just figure out how those skills work using your natural Ni+Te instead. All roads lead to Rome.
I think functions represent attitudinal perspectives, not particular skills. It's true that people with certain perspectives do tend to be good at certain kinds of skills, but just because you can complete tasks that Ne+Ti people are normally good at doesn't mean you're necessarily using Ne+Ti frequently.
imho, you would have to temporarily turn off Se and Fi in order to use Ne and Ti, which is difficult for someone whose typical modes of Pe/Ji are Sensing and Feeling.