BONUS CONTENT
(Meta: I have been paralyzed with indecisive perfectionism on this question for way too long the past day. This dynamic is no small part of why I have never posted an article or barely any comments on this site in eight years of reading it and being part of its culture. Every additional word I added to this post increased the surface area of potential errors, a trap where the more I corrected the more I saw a need for correction, the more I ran the farther the finish line seemed. It's weird since I noticed I could have just posted the question by itself and left it at that satisfactorily. I realized that I could get that easygoing feeling back and just route around this maladaptive mental pattern by labeling the post as "bonus content" to the question! This relaxes the demanding constraint of feeling like each additional word I write has to impress you. That means you read this at your own risk, sucka! No promises of formality and articulacy! I am free and can feel satisfied, yippee!) ☺️
Our quest consists of the simplest operations, each one worthy of examination. We cannot build towers of thought without a solid foundation. We cannot build better tools if we don't know how our current tools operate, and it's often good to bootstrap by using our tools on themselves.
It seems silly to ask. But I have a heuristic that that which is laughed at should be taken seriously. It is an action at the core of our epistemology. I wrote down at least a hundred questions I could ask here, and this struck me as the logical first step, the node before all others. What is the nature of the enterprise, before we chart a course to any particular destination?
So I ask: What the fuck are these question things anyway?
There's something about a conscious recognizing of what is unknown - the act of questioning being the movement from Unknown Unknown to Known Unknown (aka unconscious incompetence to conscious incompetence). What is the process of noticing ignorance?
But I want to leave this open-ended. More information on what correlates with questioning seems valuable, whatever it is. I don't know what I don't know about how I come to know what I know.
Here are generative subquestions to consider (some of them are their own can of gummy worms best left for a deeper answer another day)!
Can you Taboo "question"? What is happening in the brain when a human questions? How has its meaning and etymology morphed over time? How do other languages conceptualize the act of questioning? What metaphors are useful to understanding what questioning is? What are unusual framings of the concept of questions? What are the different kinds of question? When is a question not a question? Do animals ever 'ask questions'? Can questions be nonverbal? What does it feel like to have a question and to have that question resolved? What is the research on questions? What are their significance to human history? Do they actually exist?
Can you Taboo "answers"? How does one know when one has an answer? What is information? What is knowledge? Are answers always tentative? Can one predict when one will receive an answer? How do people go about seeking answers to their questions?
Can you compose a satisfying, useful, compact, and true model of what questions are?

I will try to focus on the "compose a satisfying, useful, compact, and true model of what questions are" aspect. To reduce the problem to something more manageable, I will regard the thought process while questioning and exclude social and linguistic aspects.
In short:
My model proposal:
- While thinking, we use 'frameworks' (expectations/models/concepts/..)
- When thinking inside of a framework, we are able to notice gaps and inconsistencies, which feels unnerving to confusing
- This causes us to search for a solution (filling the gap, fixing the inconsistency, replacing the framework), which is the act of asking a question
(- The nested, interacting, fuzzy and changing 'frameworks' make everything complicated.)
In long:
Aiyen answered "It's a noticed gap in your knowledge", which I would like to build on:
It seems to me that questions are only possible when there is some expectation/model/concept in my mind to find the gap in.
As no better term comes to my mind I will use *framework* as the term for the expectation/model/concept that the question is stemming from. One can imagine 'framework' to refer to a mental picture of some part of reality.
Now it seems to me that while thinking inside of a framework one can notice gaps or inconsistencies in the framework (this strongly reminds me of 'Noticing Confusion' from the Sequences), which feels unnerving (if clear) or confusing (if vague).
The search for a fix to the gap of the framework would then be what we call asking a question.
When doing this in a social setting, asking a question will tell others that help (in some sense) is being asked for and reveal something about the framework in use (which has many implications for social interaction).
Example
- I think that the term 'stupid question' is usually used when one thinks that the asking person is using an unsuitable framework altogether. It doesn't refer to the question itself but to the fact that 'basic understanding' (the 'proper framework') seems to be missing and thus answering the question would be pointless.
Usefulness and Summary
Although this model of Questions seems quite compact and true to me, at this point it doesn't help with moving from the "Unknown Unknown to Known Unknwon".
Pointing out that confusion plays a big role is already part of the Sequences.
Apart from hiding everything complicated behind the term 'framework', the main aspect of my model is the claim that questions always, per definition, have their origin from 'inside their box' and are a quest for looking outside of it.
To improve our tools of thinking, a better understanding of questions and their behaviour surely is useful.
In my usual way of thinking, the frameworks I am using in my mind are fuzzy and ever changing, which makes it hard to pin down and realize confusion.
This problem can be approached by thoroughly and consciously choosing one's framework of interest. One would expect this to take a lot of mental work/time, but in exchange be a more robust way to improve frameworks
(This does sound a lot like the "System 2" way of thinking from Kahnemann's "Thinking, Fast and Slow").
If it is true that finding gaps in a defined box (framework) is a natural ability of our mind (and the existence of a box a condition for this ability), this could open an approach for improving our tools.
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Final note: Until now I only read about rationality and certainly do not feel confident in my ability to contribute without erring often. Please point out mistakes that I make or basic ideas that I am unaware of.