I am interested in the orders associated to the lesser-dimensional/weaker information elements.What I am mainly hoping for some perspective on is the choice of ordering the information elements 3 and 4, basically why the third is the third and why the fourth is the fourth, as opposed to the other way around. It seems the premise of socionics model A is that an irrational base will have a stronger mental functioning in the realm of the non-preferred irrational information element of the same static/dynamic type as the base, than in the weakest rational.
For instance, http://www.socioniko.net/en/articles/gulenko-mbti.html discusses the weakest information elements of INTj and ENTp and the so-called analogues in the Myers-Briggs system, and notes how in socionics, ENTp has feeling the weakest function, rather than sensation: "The same problem arises with defining the weakest function. It must stand at the 4 th position. Therefore, it is sensing for both INTJ and ENTP. According to socionics, it is only half true: ENTP's weakest function is feeling."

It is, however, a common assumption of the Myers-Briggs typology and certain Jungian equivalent interpretations, that the fourth function will actually be rational in the rationally dominating type and irrational in the irrational type. Not that I accept this or anything as gospel, but their interpretation is that two separate forms of rationality oppose each other.

Actually I must say that this (the Myers-Briggs principle) appears to not make full sense as is, for while it may be true that the rational mind must focus its energies in one direction or another, the separate kinds of rationality concern different spheres, hence should be employed generally towards somewhat different contents. They would conflict only when apparently addressing the same issue, but at most this could lead to misunderstanding rather than there being a real issue, in so much as the spheres of activity should be separate.
What I can justify though in this Jungian model is that where one form of rationality is held supreme, the other will tend to function only within the associations permissible by and comprehensible to the other (so they may function in similar spheres while one may be subservient to the mechanisms of the other).

I think socionics model A also does however make an equally precise/rigid proposition, and my aim here is to get some justification for it. My best estimate is that the socionics analysis says for instance, with a rational base, the only obstruction to the other rational information element in the mental sphere is simultaneity, whereas perhaps it is surmised the unpreferred irrational is both irrational (hence of the not preferred orientation) and not the preferred one of the two, hence the pressure point.

On a side note, it would appear Immanuel Kant is often regarded as one of the classic Robespierre types, and he did indeed devise much theory in the realm of ethics. It was conducted entirely theoretically and attempted to render explicit and logical something which ultimately depends on people, but it does seem the ethics function might have been instrumental in part, even if his ultimate theories were full of introverted logic.