Eh, I'd say that the Fi-dom has very broad base principles he/she is working off of to form those personal values. In hearing other INFPs discuss their Fi, it's clear that the values are formed based on feeling-concepts that basically amount to fundamental principles.
INFPs are more comfortable being at odds with traditional logic, and even feel like it gets in the way of more important things.
I like this because I feel the realms that the INFP deals in most & best have little to do with logic, even if we are using a form of rational reasoning (which we are - I'll stress that Feeling in MBTI is NOT emotion). "Pure logic" can be too limiting and narrow, and frankly, just miss the point sometimes.
There was a great thread at another MBTI board called "INFP: Logic vs Rationality" that an INTP started. I'm copying some of my answers from there because I think a lot of the questions asked hit at the core of the Ti vs Fi issue.
(There are other posters' answers that are great, but I'm not linking to the thread because I don't know if that's appropriate (?).)
other MBTI board discussion said:
What is the nature of the inspection? Logic or rationality?
INFPs, in determining the soundness (or lack thereof) of one of your values, do you use slight, moderate, or extreme logical deduction, or do you just need for things to "make sense"? Do you need to get into technicalities, or do you feel that you know through general reasoning* whether or not something would qualify as X. Do you go by a) practical benefit, b) universal (multiple perspective) consequence, c) empathy ("if I were in his circumstances..."), or d) other?
I'd say b, c and d. D being an analytical process or a deduction as you say. I do tend to be satisfied with things "making sense", but I will break down the nitty gritty of an issue to make sure it's all consistent. I tend to start with that whole "knowing" feeling you speak of, which is very holistic, and I work out why I have that feeling. I make sense of it through analysis. I don't think I am as concerned with the parts as much as an INTP, but I do analyze a LOT.
I will also need to take in a lot of info and consider many possibilities (probably Ne) before I can come to a conclusion. I've recognized that my reasoning process is detached from the external, so I have to make sure I am not just pulling stuff out of the sky . However, sometimes it's hard to find anything concrete to support Feeling judgments, because they are coming from these large, vague, conceptual principles that are hard to prove externally. I don't think Ti-doms face the same challenge.
The need for harmony of feeling-thoughts can actually cause much "inner turmoil" within an INFP, which I think is experienced less in an INTP because they tend to be less focused on trying to make sense of subjective issues & often can use objective measures to support their thoughts. I think the INFP often struggles to find any external support with the realms we tend to deal with. I like to think of Fi as considering the inconsistent variable that is HUMANITY, which allows for a bending of logic to accommodate people & everything about them that is wonderfully passionate & irrational. Probably why we have a tendency for empathy & compassion, even when we think someone is being irrational. Strict logic may be at odds with this angle, but we are capable of it (see below), if the situation is clearly impersonal. However, there are times when strict logic will feel irrational to an INFP, because the situation is clearly personal. The bottom line is, TRUTH is the goal, not just some fuzzy wuzzy good feeling.
According to Gifts Differing, a Thinker prefers impersonal reasoning and a Feeler prefers personal reasoning when an issue is in the gray area and could be decided with either. So an INFP most definitely can use impersonal reasoning when a situation is clearly impersonal, and I'm sure a mature INTP can use personal reasoning when its called for.
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I think I prefer rationality and use strict logic when it's necessary. There is most certainly a "ruthless inspection" though.
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[I have] a near instant value judgment in the form of "resonating"..... it almost feels "backwards" at times. I have a strong feeling that's a "conclusion" and then I work it out through reason to verify that it's valid.
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