I replied to Eyeseecold, but I shall repost what I've said here:
I looked at the Socionics site several years ago, and was interested to see that their model is similar to the one outlined by Walter Lowen in "Dichotomies of the Mind." He says the same thing as they do about the flaw in the MBTI's J/P category, and, all else being equal, it's hard to disagree. Where I part company with them is their solution to the problem. Maybe the issue ultimately comes down to what one understands J and P to mean.
As far as I'm concerned, Katherine Briggs created a model of temperament rather than type. Her original classifications, after all, were Spontaneous, Sociable, Executive, and Meditative. She couldn't make this model work until she read Jung's "General Theory of Psychological Types," which led her to adapt her system to his description of the functions.
The first conclusion she reached was that her Meditative types were equivalent to Jung's Introverted types.
She thereupon associated her Sociables with F types and her Executives with T types. What gave her a problem was that her Spontaneous category lumped together what Jung was calling N and S types. So she worked to separate the two, and now she had four categories like Jung, but her Meditative Introverts appeared to be in a fifth category by themselves.
She solved the problem by seizing on a single paragraph in Jung's "General Theory," which introduced the idea of the auxiliary function. It said that the auxiliary function is different in every respect from the dominant.
Supported by that paragraph, Briggs decided that F, T, N, and S must be Extraverted when they're dominant and Introverted when they're auxiliary. This got rid of her Meditative category, but it gave her another problem. How would one know whether F, T, N, or S was dominant in its Extraverted form? That's why she invented the J/P classification, again, borrowing the terms from Jung. A J would mean that the Judging function was Extraverted, a P would mean that the Perceiving function was Extraverted.
My objection to her new category is that it not only screwed up Jung's understanding of rational versus irrational types, but, as I've stated (to Eyeseecold), it screwed up the category of Sensation, which Jung associated with a good sense of time, factual precision, and a realistic appraisal of risk and resources. These somehow wound up in the J column, and we associate them, in the dullest way possible with Si, reserving Se to kinesthetic and artisan skills of one sort or another.
It may be noted that Jung did not regard E and I as a separate category of any sort, never mind P and J. He said, in fact, that attitude would not even be apparent UNLESS a function had been differentiated. That is, until some kind of selective functional preference is consistently determining one's choices, one doesn't display a dominant attitude. One is responding, rather, to circumstantial conditions, without free-will selectivity. Myers and Briggs appear to regard the attitudes, rather, as innate aspects of temperament, which would be apparent even in the absence of functional preference.
In any case, my opinion is that Briggs' Spontaneous, Sociable, and Executive categories are pretty much exactly what Keirsey means by SP, NF, and NT. And I would maintain that the ongoing problem with N and S in the MBTI community has its roots in the fact that Briggs didn't originally distinguish between them, whereas Keirsey reserved the parallel SP classification for Se alone.
At this point, temperament theory and MBTI theory have converged so utterly that the distinction hardly matters. But I think that the Socionics folks have focused too narrowly on the J/P confusion without recognizing that they're no longer talking about type, never mind being faithful to Jung.
For one thing, Jung never specified 8 cognitive processes. He spoke of two rational functions, two irrational functions, and two attitudes. An INTJ, in Jung's system, would be modeled Ni-Te-Fe-Se. A function is differentiated in the attitude that comes the most naturally to a person, or is most supported by culture, and the other functions ally themselves with the unconscious instinctual life, where they serve to support, conflict with, negate, or broaden the dominant goals.
There ARE no missing four functions here. In Jung's model, an Introverted type will naturally attempt to Introvert the other three functions when s/he becomes aware of content that supports the dominant. Good type development requires relating to the auxiliary, even if it's not comfortable, which offers more contact with one's unconscious instinctual life.
This, in particular, is something I've come to see differently than I did years ago. I don't see any need to talk about 8 separate cognitive processes.
The functions are simply orientations -- the means by which our unconscious emotional and physical experiences become available to our higher mental functions, moving them into the stream of consciousness. To differentiate a function means to give greater value to those choices where emotion and reason are largely in synch, or where the inhibition of emotion affords a cultural advantage.
This is NOT an inborn pattern. You need experience, a sense of what's worked in the past and what you want in the future in order to establish a consistent orientation. It's almost like setting up a nuclear reactor -- our emotional life gives us the energy we need to accomplish anything, but the functions are like the fuel rods that direct the energy in a stable way into our investments. Our dominant function allows us to inhibit some of our natural reactions for the sake of our conscious purposes. That's why we feel like we have free will. We commandeer or block natural tendencies for the sake of aspiration or goal or larger purpose.
Attitude is the closest I think type validly comes to talking about temperament. But even so, the vast amount of people are adaptable; that's why we're successful as a species. They ultimately develop an habituated typological identity, which may not change, but we're all born with a great deal of potential to adapt to any number of environments.
In general, I think most type models are consistent on their own terms. But I find it easier to use MBTI terminology, because that's what most people know. I simply understand P and J in my own way.
The best example I've got is that we all have two different ways that we deal with mathematical relationships: a left-brain mode, which results in verbal shortcuts (like the multiplication table - 2 x 3 = 6), and a right-brain mode, which allows us to grasp relationships between quantities without specifically calculating (like recognizing that 1,203 + 6 couldn't possibly equal 17).
The left-brain mode allows us to perform precise calculations, which are usually inculcated by education. The right-brain mode allows us to grasp relationships in a way that draws on natural human capacities (spatial logic).
So although the MBTI treats INTJs as though they were rational types, even though they're irrationals in Jung's system, and INTPs as though they were irrational types, even though they're rationals in Jung's system, it doesn't make any difference to me. In my view, INTJs are using left-brain Thinking -- they want to improve the systems they encounter in the outer world, and INTPs are using right-brain Thinking -- they feel a sense of truth in their very bones and believe it ought to change damned near everything.
Neurological research shows, in fact, that people depend on one brain hemisphere for familiar tasks, but draw on both when they're doing something new. Habituation tends to orient us in a particular way -- unless something happens that we don't understand, moving other parts of the brain to get involved.
INTP
I still think it's inconclusive.
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