Quote Originally Posted by Phaedrus
I have said before in some posts that I am inclined to think that the J/P dichotomy is very important. Jung took his starting point at E/I, Keirsey takes off at S/N, but if we start from J/P we will be able to start from something that is observable. I believe that it also reflects a fundamental difference in attitude towards life. J and P types have different world views in a sense (Lenore Thomson has written something about this). And that difference can be seen and it can be felt when you interact with people.

One theory is that what people think of as J and P behaviors map to rational/irrational. The other theory (put forth both in MBTI and in the Socionics quadra descriptions) is that personalities with a Ti or Fi structure are P and those with a Te or Fe structure are J.
This is slightly inaccurate. Both Socionics and MBTI think that J and P behaviors map to rational/irrational, if we refer to the types as whole units. There is no other theory since what MBTI says about personalities with a Ti or Fi structure is not that different from what Socionics says about them. The way an INTP thinks is described the same way in MBTI as an INTp's way of thinking is described in Socionics. They use different words (like Ti and Ne in contrast to and ) to refer to the same empirical reality.
Really? I remember going through the MBTI manual, and seeing clearly that MBTI sees IPs and EJs as the "rational" types and IJs and EPs as the "irrational" ones. Also, I remember reading that the Myers/Briggs team came up with the J/P distinction as something they felt was more observable than rationality/irrationality. It seems pretty clear from that that in MBTI theory, rationality/irrationality refers to a different distinction than J/P, and different from the way rationality/irrationality is described in Socionics.

As far as I'm aware, it's only Socionics that equates rationality/irrationality with J- and P-like behaviors.

If you see some reliable information to the contrary, pass it along.

As to the definitions of the functions being different, well that is a reasonable way to explain the differences in how the theories come out. But actually, many people in Socionics tend to define and similarly to the way they're viewed in MBTI, which is maybe why they think you're INTj.