Interesting idea. It's certainly possible, but I would expect that there are many FJs who have adopted the idea that it's best to withold judgement from the external environment and to just comment on what they perceive, the latter being less judgemental in nature.
This is of course assuming that I haven't used judgement/perception out of context.
This does seem to correlate with my experience sometime that Fi dominants can become quite attached to their belief system, where as I've seen Fe users take on a more moral relativity approach when it comes to debating about ethics. Granted it's a limited sample, and therefore could be wrong.
Yes, those are called introverts. Think of each introverted type as performing the same functions as its extroverted counterpart, just giving more priority to the introverted function.
Take ENTP for instance--the theory says we have dominant Ne and auxiliary Ti. Ne has the most influence on our dealings with the outer world, so we're scattered and restless and frequently disorganized externally, but then Ti takes those patterns from outside and organizes them into systematic criteria by which future patterns may be judged.
We are Perceivers because we extrovert our Perceiving function, Ne,
not because we are dominant in a Perceiving function.
The important distinction here is that P/J is determined not by whether your Perceiving or Judging function is dominant, but by which of your top two functions (S/N or T/F) is
extroverted.
Just follow these easy steps:
1) Your middle two letters tell you which two functions you use best. One will be a Perceiving function (S/N), which gathers information, and one a Judging function (T/F), which makes decisions based on that information.
2) According to the theory, one of these two functions will be introverted, and the other extroverted. The P/J tells us which of the two primary functions is the
extroverted one, because that function is responsible for most dealings with the external world and environment. The outer world doesn't really witness the processes of introverted functions; they are linked inextricably to personal perspective.
3) Now the I/E tells you which of the two functions you give most priority to.
Example:
1) Say I'm an ISFP (if only!) So my best two functions will be Sensing and Feeling.
2) The P indicates that my Perceiving function is extroverted, in this case, Sensing. So we know that one of my top two functions is Se.
3) By process of elimination, since one of these two functions must be extroverted and the other introverted, my other primary function must be Fi. So from a functional theory perspective, SFP = Se+Fi user. (Sensing-Feeler who extroverts his Perception and introverts his Judgment.)
4) Finally, the I tells us that from Se and Fi, the Introverted function is the one that will get highest priority, on average. Now we have Fi+Se...ISFP = Sensing-Feeler who extroverts his Perceiving function (Se) and introverts his Judging function (Fi), but gives more priority to the introverted one...which is largely unseen and unheard by others. This explains the introvert's apparent social withdrawal and desire for alone time.
The theory goes that FJs who withhold their feeling judgments, as you mentioned, are probably IFJs. They're still Js because they extrovert judgment and introvert perception; in the case of IFJs, they just happen to use that introverted Perception (dominant Si/Ni) more often than its extroverted Judgment counterpart (Fe), and thus appear much more reserved.