Why do INFJs seek to find their own personal validity in what they believe, think, and do? INFPs seem to just simply assign value to some things and not others based on how they feel about them, but INFJs are constantly trying to prove what does and doesn't have value so that they know how to feel about them.
I saw two sections to your question.
Part One:
seeking of external validation to gauge whether the direction headed is sound.
Fi vs. Fe
I believe neither is superior. One is simply better suited to someone cognitively arranged INFPish, the other better suited to someone cognitively arranged INFJish.
I sense I am at my strength when I go through the external engagement process. In my fluidity to what exists externally, I am open to process whatever information may be presented. I do not feel settled in a decision until it has been weighed against an external measure. If I were to attempt decision-making without seeking open engagement to what exists outside myself, I fear making decisions that lack essential understanding.
Eventually I sense when it is time to pull back in and make the decision. Once I'm there, I may experience social discomfort at dissenting judgments, and choose to limit my company to places where I feel comfortable in my decision, but my decision remains made. Unless I willingly choose to seek out another distinct decision-making process.
Part Two:
a drive to defend decisions, or proposed decisions, with logic.
Tertiary Ti
It's no surprise to me that Duty presents here in this thread as they do. If their type is INTP, then having a strong support of logic for decisions would be elemental to the conception of decision-making for them.
It is not so much for me.
Duty said:
Sounds like INFJs, for personal growth, probably go through a lot of strides in being able to explain their reasoning. I mean, if you can't explain why, then it won't be very persuasive or meaningful to others. I think Einstein or Feynman (sounds like a Feynman quote, but for some reason I want to say it was Einstein) said something like, "A scientific theory, no matter how elaborate or correct, is not persuasive if it can't be explained to lay people, including children."
There are times when I may choose to attempt explanation of my positions with reason, but generally when I'm engaging with others, I'm submitting to their wisdom and allowing myself to soak up what they can offer. Once I've made a decision, I feel little drive to persuade.
I may, however, feel a drive to present. Logic is generally not necessary for this presentation. I tend to choose metaphor or personal story to present. If someone sees something of value in what I share then I welcome them to take it. If they do not, then they do not. /shrug