I want to put down some of my thoughts about the functions (IMs? IEs? Whatever, I like the word function), and I've finally actually written something. Would love to hear people's thoughts, agreements, disagreements, etc. My plan is to eventually tackle all of the functions, starting from an aspectonics POV and broadening out to an image or metaphor that captures how I think about the function. I also note the level of abstraction embodied in each function because I think that has a lot of bearing on the incidental elements of type, which has less to do with how information is processed fundamentally and more to do with the habits of thought that are natural to each type, i.e., IEIs are spacey because they have two very abstract elements in their ego; SLEs seem more on-the-ground (if not "grounded" which is more of an IJ descriptor) because they have two very concrete elements in their ego. That's a very simplistic version of the idea. Anyway, here are the thoughts. Just Fi and Ni for now, more to come soon. Comment, agreement, disagreement, hatred, elaboration, appreciation, refutation, etc. are all welcomed and desired.
Ni. Internal dynamics of fields. Arguably the most abstract function: the internal must be inferred from the external; relationships between objects are mental constructs (unless you affirm the reality of the Platonic Forms); dynamics requires the assumption of identity-through-time.
Ni is interested in how relationships change over time. Imagine a Newton's Cradle. Several objects interacting with each other over time in one dimension. Now imagine that you add another Newton's Cradle perpendicular to the line of the first Newton's Cradle (technically the 2nd Newton's Cradle will have four balls instead of five, such that the ball at the center of the Axis is "part" of both Newton's Cradles. But that's actually not a big deal). Then mess with the weights of the balls so they're not all equal. Then add more and more Cradles at different angles. Add more cradles that bisect the lines of other cradles at different points. Create a whole complex system of pendulums that are all interacting with each other at different speeds and in different ways and everything. That's what Ni is. It's a way of looking at this mess of interactions and instantly perceiving particular pieces of the puzzle, such as "oh, the third ball from the left must be the largest." Then you start making predictions about the system: "oh, that ball in the center is about to break off of its chain and go flying out of the system." Then you start guessing how your action could change the system: "You know, if we doubled the weight of that ball, we could keep the center ball from breaking off of its chain for at least ten more minutes." Because Ni is a perceiving function, Ni-egos experience this as a sudden realization, an intuition.
Fi. Internal statics of fields. You could also make a case that statics require greater mental gymnastics (greater abstraction away from purely perceptual reality, from sensory data) than dynamics, so Fi could theoretically be the most abstract of the functions.
Fi is interested in what remains stable about relationships over time. I compare Fi to the smell of a room. How a place smells is a combination of a crazy number of factors. Each item in the room gives off a particular smell (that is, has a particular relationship to entities with olfactory systems). And the particles that give off those smells themselves have interactions. But we don't smell each particular smell, we smell a combined thing that is "the room," even if one particular smell dominates. That "smell" is the feeling that Fi has. The analogy is misleading insofar as a smell is a perception, whereas Fi is a judgment. So, knowing that smell is the strongest sense tied to memory, we might say that Fi, rather than being the smell of the room, is the immediate feeling (good, bad, happy, sad, annoying, etc.) that the smell arouses. Some smells are just bad. Some smells are really nice. Some smells don't necessarily have a value judgment, but have a strong association, so their value is as complex as the thing they associate with. And just as you immediately smell a room when you walk into it, and it immediately smells good or bad or indifferent or whatever, so Fi immediately has a feeling about whatever experience brings to it.
Fi is also static. It takes a lot to change the smell of a room. You have to introduce several totally new components, and/or pump those components out at high volumes. And even then, you're often masking the actual smell of the room, rather than really changing it. Fi would dismiss such a masking as a temporary change that isn't "real."