Everybody post your definitions of the IMs, go! Feel free to follow the format I have established or make your own.
In order of the ones I know best:
Description: Tracing things forwards and backwards on temporal and causal lines (as well as lines of necessity, as in x is necessary for y, and lines of logical priority, etc). Working with limited information through "emergence": Ni uses the pieces of evidence at hand to imply a whole larger than the evidence available, e.g., Bones constructing a narrative of a crime from three or four pieces of evidence, looking at an engine, an exhaust pipe, some wheels, and a steering wheel and guessing what a car is like.
Personal Experience: I experience Ni as narrative-constructing most frequently: seeing a few things that happened and coming up with a narrative relating them all which is temporal in nature. I also tend to view things in terms of their formal aspects; what I mean by that is, I view my brown chair as: brown, chair, sitting-object, furniture, made-of-wood, held-together-by-screws, university property, etc.
Aspectonics: Internal Dynamics of Fields. Ni is concerned with implicit or invisible aspects of a situation (in the case below, the abstracted properties of the car parts, rather than the physical parts themselves), and how they change in relation to one another over time: how would an engine interact with an exhaust pipe, and how would that relation change when you mix in the wheels, oh, and then I guess that explains where the steering wheel comes in... or, to provide a more "real life" example: you have x amount of dollars of subprime mortgage loans. You then have forces a and b acting on the market. And you have Bank m with its set of properties. How will these three interact over time? Or how did they interact over time in order to create the subprime housing crisis?
Description: Essential (i.e., unchanging) connections between things established by explicit (e.g., reproducible) means. Truths contained in the mind of the individual rather than in the world at large (introverted), but arrived at through means that are available to everyone and clearly defined (explicit). Discovering contradictions between two propositions. E.g., It was stated that engine of the car cannot start itself. Therefore, there must be some source of power external to the engine in order to achieve the objective of motion.
Personal Experience: I experience Ti as a dividing function, especially in exposing contradictions and finding really deductive reasoning. I usually encounter it in an intellectual arena. Lots of concern with whether a new idea or claim or event fits with the established standard or not; things that do not fit with the established standard will be considered "stupid" until such time as they are proven to be derivable from a higher principle.
E.g., Principle 1 states that it is unwise to marry an ugly woman (this principle has been derived from experience and observation). However Principle 2 states that if one's girlfriend is pregnant, one must make an offer of marriage. An individual marrying an unattractive woman would be ridiculed, until it is revealed that Principle 2 (which supersedes Principle 1 for reasons the Ti-ego would have difficulty articulating to you) is in effect.
I also experience Ti a lot from my dad. I can see how he has developed principles and rules over time that tell him how to do the various aspects of his work, such as "always save an editing file every five minutes" or something like that. The relationship between work and saving is such that it is important to save frequently. This rule has been tested through Se experience: when I follow the rule, I achieve my goal; when I do not follow the rule, I do not achieve my goal.
Aspectonics: External statics of fields. Concerned with unchanging relationships that are relatively more explicit in nature. Developing theories as to the properties of the relationships between objects. When paired with an extroverted perceiving function (as in all Ti-egos), Ti will create hypothetical rules, which they will then test according to the EP function (either by imagining alternative scenarios and questioning their likelihood, or by seeing if the rule helps achieve their goal in the real world).
Description: Diagnosing and manipulating the intangible motion that occurs in everything from corporations to friendships to individuals. Unlike Te, not concerned with the explicit factors (such as the rules of subprime loans, or the financial state of a corporation, how much money it had lent out, etc.) but with the invisible factors (were people focusing their energy on themselves; were they thinking about the impact of their actions on others; when you mentioned mortgages, were they attentive and thoughtful or dismissive and unthinking?) that influence a situation. And as an EJ function, the information content is as much "how can I affect the implicit motion of this situation" as "what is the implicit motion of this situation."
Pragmatically, the active and habitual manipulation of the emotions of a person, a room, a company (as in motivational speaking and many forms of corporate training designed to change the "community atmosphere"). In trying to convince someone of something, the mode of convincing is far more important than the logical or even ethical argument at hand (pathos, rather than logos or ethos). E.g., "black momma face": angry black women communicate with their children through an emotional energy rather than any real logical argument or even the consequences; the consequence is the emotional whatever.
In a broad-based sense, large-scale historical movements can be seen in terms of Fe, insofar as a change in the zeitgeist is a change in the implicit aspects of an object (i.e., a state, or the world as a whole). "The Times They Are A-Changing" can be seen as an Fe statement: it's not any one specific thing or even a set of different things; there's just a different spirit about the place (also can be read in terms of Fi, but more on that later).
Personal Experience: I experience Fe as knowledge about how to comport myself in a situation, essentially. How can the implicit signals I send out affect the implicit properties of this atmosphere? I'm depressed; is that making everyone else depressed? I'm happy; are others happy alongside me? Also, subtle changes: when you bring up a certain movie, does it get a positive reaction (note-to-self, bring up movie again). When you start talking about 90s music, who engages in the conversation and who stops caring? What will reengage the people who stopped caring? It's almost like sight, really: it's like I can see spots and pockets of where the energy is high and where the energy is low, and how that changes over time, like a 3D graph of internal state draped over the crowd.
Aspectonics: Internal dynamics of objects. How implicit aspects of a situation change. Internal motion. Not much more to say.
Fi: A set of principles and rules for the relations between objects, but which is internally derived. It has no fear of contradiction (although it usually functions according to an internal logic that cannot be made explicit). Experienced as a "feeling" about something, fundamentally whether it is right or wrong, okay or not-okay, good or bad, etc. Not judged based on an external metric such as "will this help me achieve my goal?" Judged on an internal metric: how does this fit with me?
Fi would look at the subprime loan situation and just see "BAD" written all over it, but not necessarily have the logical principles to elucidate why it's bad, why it contradicts some central principle (my SLE friend, on the other hand, has an number of central principles the subprime situation contradicts). It could be a look given by a CEO that sets off the internal alarm, or it could be a fact about the situation (if the Fi-ego has enough training in the area to be able to interpret the facts reasonably well).
The fundamental assumptions we make as a society, taboos, etc., are associated with Fi. Fi is the ur-knowledge, the judgments that we do not question or even notice ourselves making. Much like Ni is the lens through which we view things, Fi is the first test we apply to judge good or bad, whether we value it or not. It is always an Fi judgment when we are revolted by incest. We may come back and add SeTi reasons: it prevents us from achieving the goal of having healthy children, but the initial revulsion reaction was Fi in nature. A good example of Fi-based societal change is the view of homosexuality. Whereas homosexuality once evoked a primal, instinctual "ew" reaction from people, now the stronger "ew" reaction is against those who persecute homosexuals.
Personal Experience: I experience Fi as a system of feelings about various topics that I can't quite figure out. It leads me to tread lightly, because I do not understand what exactly is right and what exactly is wrong. And yet, everyone else understands it, or so it seems. Granted, in a broad sense I understand the rules, and I can generally be diplomatic enough to dance over landmines, but from a conceptual standpoint it is irritating because I cannot figure out how it works.
I see Fi in others in an assertion of rights, of how-I-am-to-be-treated, focusing on this aspect where I would prefer to just say "x is wrong, y is right; punish x, reward y" or "x is helping us get to the goal; y is not helping us get to the goal; get rid of y, keep x" without the messiness of personal rights and how-I-am-to-be-treated. On the positive side, Fi seems to lead Fi-egos, for reasons unknown, to a genuine level of concern for others, especially those close to them... that is more self-effacing than I am accustomed to.
Fi would also notice Zeitgeist change, but it would not be the times they are a-changing, but my-experience-of-the-times-is-changing. In situation y, I used to feel x; now in the same situation, I feel z instead. Something has changed.
Aspectonics: Internal statics of fields. Much like Ti, it's a series of rules for how things work, but these rules are not explicitly derivable from any experience (although they are surely rooted in experience and knowledge). They are just known. As such, they are more effectively applied to situations which are themselves implicit and ineffable, such as "what makes a good relationship" or "what is a healthy working environment for a company" or "what sort of care do infants need in order to grow up well" or anything really, where the decision cannot be made deductively alone. The question "how then shall we live," while it can certainly be answered in a Ti fashion ("well, given psalm 32:5, and Mark 11:22, the reasonable deduction seems to be..."), it will always have an Fi base of fundamentally considering something more right or more wrong for reasons we cannot derive from first principles but just know (moral intuition).
Alright, that's all for now kiddoes. I think I have relevant things to say about Te and maybe Se, but I'm pretty clueless when it comes to Si and Ne (ESPECIALLY Si). So yeah, everybody, post your definitions/commentary on each IM, and then try to leave at least one comment on somebody else's description saying one thing you really agree with and one thing you really disagree with, so we can sort of see what aspects are controversial and what aspects there's a broad base of support for.