Hi Caerulea, thanks for your good questions. I will try my best to answer your questions here.

Your opening paragraph explains neatly the three intentions you have for this text:

1. Why we should look beyond the Big Five for information on cognition.
2. Comment on why you stick to MBTI contrary to what people believe.
3. Describe the real reason, which is related to the reality of cognition.

What I am wondering reading the first paragraph is: Why did you choose to 'defend' MBTI this particular way? If you could explain this, I believe some interesting connections would surface. And also maybe give a written answer to why you chose the title. 

1. Why we should look beyond the Big Five for information on cognition.

I wrote this post in response to someone who said that the MBTI was inferior to the Big Five because it was less scientific. I just wanted to explain why we had to broaden our horizons a bit and have an honest look at the differences between the MBTI and the Big Five, and what we could expect to get out of both. I think that if the field of psychology would broaden their horizons a bit, we could make a lot of progress on the science of cognition. There an infinite number of different theories of cognition that could be proposed. I just think that by explaining some issues with the Big Five, I could encourage people to take a look at new theories. Just asking 200 questions of a human and finding correlations is pretty clearly not going to result in not going to result in the be all and end all of psychology. Maybe if you trained a neural network on the answers to those questions, looking at the weights might give us more insight, but just looking for simple correlations is clearly going to result in a very shallow understanding of the brain. More advanced aliens than us wouldn't be impressed if they saw that our understanding of cognition was limited to some researcher asking a bunch of random questions and finding a few factors that could predict how people would answer the questions to a limited degree.

2. Comment on why you stick to MBTI contrary to what people believe.

This point leads straight from point one which is that the Big Five really isn't that great. Given that, I am completely open to exploring any theory of cognition I come across. There could always be more theories to explore but the MBTI is by far the most promising theory I have come across. I find that if you can find multiple people of the same MBTI type, you can notice a lot of similarities. That seems to me like strong anecdotal evidence to suggest that it is a good model. If you want to try this experiment for yourself, you can go to CS Joseph's list here or you can try with A Little Bit of Personality's list here (scroll to the bottom of the article). They both have their own theories for subtypes as well to give a more comprehensive picture, CS Joseph has Octagram and A Little Bit of Personality has subtypes (you have to create a free account to view). So, when you combine that the Big Five isn't that good of a theory with the anecdotal evidence that the MBTI is better than the Big Five when you compare people with the same traits in both, it makes sense to conclude that the MBTI is the better theory.

3. Describe the real reason, which is related to the reality of cognition.

Here I explain that the real reason I believe the MBTI might be worth taking a look at is because if you open-mindedly explore what the brain does, the MBTI just at an obvious level seems much closer to describing what it does than the Big Five. While the Big Five will describe that the reason you decided to go to a new restaurant was because you were high in openness and low in neuroticism, the MBTI can describe you being told about the restaurant activating through your extraverted sensing and you assessing whether you would enjoy it through introverted sensing (looking at similar past situations) and introverted intuition (imagining the likely course of events that would play out if you decided to go there). That is by any account a much more in depth view of cognition than can be provided through the Big Five. This simple classification of cognitive functions seems to have quite a lot of validity in terms of how people actually think - I would not take that lightly.

What I am wondering reading the first paragraph is: Why did you choose to 'defend' MBTI this particular way? If you could explain this, I believe some interesting connections would surface.

First, I described the issue with the current model (the Big Five).

If you want to propose a new model, you have to first show where the current model is flawed.

Second, I described what anecdotal evidence I had to support my model (the MBTI).

If you want to propose people research something, you'll have better luck if you first show some anecdotal evidence to suggest your hypothesis is correct.

Third, I described why this matters (because understanding cognition is the holy grail of psychology).

If you want to propose people research something, you'll have better luck if you explain why the research matters in a broader sense. For this point, we could imagine how I could talk about the importance to managers in professional settings and to people's personal relationships to be able to understand their and others' cognition accurately.

And also maybe give a written answer to why you chose the title.

I believe the original title was something like "An Open-Minded Exploration of the Nature of Cognition" but I changed it to "In Defense of the MBTI" to more accurately represent the thesis of my post that the field of psychology should look into these MBTI-adjacent theories further. For that, I realized I needed to defend the MBTI especially given how bad the MBTI test itself is. Basically, I felt like a bunch of corner cutting by MBTI theorists had led people in the field of psychology to write it off entirely and that the MBTI needed to be defended so that it wasn't equated with the work of all these corner cutters (including the Myers-Briggs company itself) which are commonly associated with the MBTI.

The second feedback I have is with regard to the last paragraph. Where you urge more psychology research on the area, as well as inform us about sites relevant to the field of "MBTI-adjacent theories". Here I am wondering what the direct link between your title, your intention and writing this paragraph is.

Unfortuantely, I haven't yet seen a scientific exploration of all the things posited in these MBTI-adjacent theories but I think it is pretty clear that the field of psychology needs to start taking this seriously, looking into the nature of cognition, not just looking at what people answer to simple questions on tests because of the flaws of that method. There are a lot more to these theories than I have covered in this post. Some good resources to learn more about these theories are CS Joseph's YouTube channel and alittlebitofpersonality.com.

This last paragraph relates to my intention with writing this post which was as a call to action for these theories to be studied through experimental methods and to be developed further so we can develop models for describing cognition ever more accurately. Since I felt like the MBTI is a good starting point for understanding cognition, I thought that by defending the MBTI here on LessWrong, this would be studied further and psychology would be able to develop its understanding of the brain rapidly. I watched a video a while back on paradigms (sadly it seems it is gone) but it is where the paradigm shifts where science is able to make progress and people are consistently unwilling to change paradigm but that is where what I would call real science happens. I gave links to these MBTI-adjacent theories so people could take a look for themselves.

However, the overall feeling I get from reading your post, isn't that it is a post with a specific goal, using one particular method, but a post using several simultaneously. It is an expression of the direction of your own thoughts, beliefs and ideas; a meta-overview of your reasoning behind your support for an improvement of the MBTI. Moreover, it is like a meta-dialogue with imagined opponents in the Big Five vs MBTI debate. Thirdly, it is exploratory and open-ended with regard to cognition and MBTI. So it has a lot going on at the same time.
Which brings me to my next point, acknowledgment.

I tried my best to write the post without an agenda other than finding what cognition is really about, trying to see reality as it really is at the essence of science. I would say this is only secondary to another tennet of science which is broadening your horizons beyond what is already the consensus and being willing to look beyond the Overton window for things beyond what people think could possibly be true.

I could have said I think this theory is true and that one isn't, but really I have no idea. That's why I decided it was better to write this post to explain the direction I took in trying to understand cognition, and from there, others could benefit and hopefully me too. The MBTI vs Big Five debate was a reflection of my reasoning as to which one was a better starting point for understanding cognition.

Even though you could say your post needs sharpening and precision, the way I see it, it is more important to acknowledge it as an expression of your versatility in understanding and your ability to juggle different things simultaneously.

I would say my post could do with sharpening but it's not really within my ability set to be able to do that sharpening myself. I wrote the post mostly to provide information to others who are better at that so that they could study cognition further. I definitely juggled a lot in this post and I think it's important for science to move forward that we have people who can explore lots of different theories and see which ones make more sense, and also the people who study the theories more in depth to find the nitty gritty issues and can refine them all into a more comprehensive theory. (In the MBTI theory as I understand it, the first group would be the Te users and the second group would be the Ti users.) Both are necessary for science to move forward.

You have already discovered things I wasn't aware of, and I believe that if you continue, your contribution will undoubtedly be even more substantial.

I think a lot of that is just having a commitment to trying to see things as they really are. As I mentioned in another comment, I had the affirmation: "I do not limit my horizons". This was vital and I believe the attitude to explore things instead of limiting where you will explore is vital. Anyway, thank you for you comment as it gives me the inspiration to continue working on this and myself in general in terms of keeping a horizon-not-limiting attitude.

I also believe that many of your paragraphs are seeds that can sprout into interesting texts, if given the attention.

If you have any ideas, let me know.

And finally, some of my thoughts:
"CS Joseph theorizes that the cognitive functions are something like 100 rpm - 75 rpm - 50 rpm - 25 rpm - 20 rpm - 15 rpm - 10 rpm - 5 rpm"

I looked at the video, and this is a continuation of the original thoughts of Jung, as far as I know. From 'Hero' through 'Demon'  
 https://www.careerplanner.com/8CognitiveFunctions/Cognitive-Functions-Simply-Explained.cfm (I'm not familiar with this site, or endorse it, it just had a nice overview to show all the personality types as well as all their functions.)

In my own experience, when I experiment with developing functions directly, I can affirm both Jung- and Joseph's claims to a certain degree. There is an underlying dynamic between all the functions, and they are not operating at the same speed. And I also agree with CS Joseph in that these limitations aren't necessarily bad, they open up for human relationships and collaboration, to complement each other.

Yeah, CS Joseph extends the original theories of Jung as well as those of others who were expanding on Jung's theories. It is definitely an interesting question if you could, let's say, get 35 rpm of each function or you could get this spiral pattern of 100 rpm all the way down to 5 rpm, which would be better? Of course, I'm not really sure if that would be possible because of economies of scale within a cognitive function in the brain, but if that is a good model, it is rather interesting that evolution chose that over having 35 rpm of each, and I can definitely see the advantage, especially when you consider that humans are social animals so they can complement each other.

I could say more, but to keep it withing the bounds of your text, I'll stop here.

Don't limit your horizons or mine for that matter.

I hope this comment is useful to you in some way, and welcome you, as a senior newbie, to the site. :)

I appreciate that you took the effort to write it and it definitely gives me more inspiration to work on this. As I said, if you have ideas for elaborations on this, let me know.

Kindly, one Z followed by five more

Link to video to try for myself?

How will you use psychotherapeutic techniques to attempt to achieve AI alignment? Can you give a rough overview of how you think that might work?

So,

Hypothesis: Cognitive functions are antagonistic as predicted by the MBTI.

Null hypothesis: Cognitive functions are not antagonistic.

So, let's say we made an experiment and made the subjects do something that required extroverted feeling and then after we made them use introverted thinking. We could test if that is harder for people than other combinations of cognitive functions.

So,

Hypothesis: People will have a harder time using a cognitive functions when they have just used the antagonistic cognitive function.

Null Hypothesis: People will not have a harder time using a cognitive functions when they have just used the antagonistic cognitive function.

Also, in terms of the specific hypotheses:

1) Basically, the idea is that any given flow of information could be said to be divided into one of the eight cognitive functions and there would be few exceptions where you couldn't divide a flow of information in the brain into one of introverted thinking, extroverted thinking, introverted feeling, extroverted feeling, introverted intuition, extroverted intuition, introverted sensing and extroverted sensing. So, null hypothesis: these categories either fail to describe a large amount (say 10%) of the information flows in the brain or a large amount (say 10%) of information flows could be said to fit into multiple categories. Obviously, the other issue here is that we might just have a random set of points and draw a line around each shape and find any number of different ways to separate things but I think that the functions are distinct enough that we can avoid that possibility.

Just briefly:

1. Introverted thinking: Figuring out what you think about something (comes to a single conclusion)
2. Extroverted thinking: Thinking about lots of different possible conclusions you could draw about something
3. Introverted feeling: Figuring out how you feel about something (comes to a single conclusion)
4. Extroverted feeling: Thinking about lots of different possible ways you could feel about something
5. Introverted intuition: Figuring out what is my future and willing yourself to put it into action
6. Extroverted intuition: Figuring out lots of different things you could do
7. Introverted sensing: Remembering what actually happened in the past
8. Extroverted sensing: Seeing what is actually happening in the present

2) This just means that these distinctions actually allow us to make useful predictions about people. So, for example, I gave an example before, of being informative vs direct, which was something that as far as I'm aware of the factor analysis tests have trouble answering. So, informative people would tend to say what they observe where as direct people would tend to talk in terms of how other people should think about it based on their interests. So, I gave the example before of the direct person saying "Can you go get some more milk?" vs the informative person saying "We don't have any milk". Admittedly, I'm not sure about the specific details of which types are each, but I think the fact that they claim to be able to determine these things should give us pause for thought. Honestly, this criteria is probably very easy to meet so I'm not going to give it a null hypothesis.

3) Different people prioritize the cognitive functions in different orders. Basically, the null hypothesis here would be that within 10% or so, different people use different cognitive functions about the same amount.

I hope that clears up what I meant by the hypotheses. Also, don't be condescending. I think it is a sign of arrogance and you must as a scientist always be willing to question your conclusions. I assume it is frustrating to see people trying to stir up a theory you already debunked. That said, I think the claim that is "superior stuff" is clearly flawed. While it may be superior at the moment (as was the model of the planets going around the Earth when the Copernican model was first invented was), until Big Five or Hexaco can get around the issue of measuring people's unintrospective self-reports, they will not be able to describe all aspects of cognition as I argued in this article. The MBTI as it's used in pop culture is total hocus pocus as I've discussed but the original MBTI was created based on the cognitive functions that Jung developed in his therapeutic practice and I think there's a good chance that the cognitive functions hold (though I don't have super good proof). As I mentioned in another comment, the cognitive functions match up with EEGs, and MBTI types actually affect how people show up on the EEG which is honestly a miracle, especially considering how bad the MBTI tests is probably mistyping ~60% of the people who take them (sorry, no source again). Anyway, of course, I don't know anything but I just wanted to open people's eyes up to this theory about cognition, even if there is a good chance that it is flawed. That said, until someone shows me how it's flawed, I don't see a reason to not try and improve the theory until it can be accepted into mainstream psychology (even if the probability is low in an absolute sense (just because the model is probably flawed)).

You understand what I said about how cognition itself is required to answer the questions on the test? I think a purely factor based approach will be unable to capture this variable. That said, I will admit that I don't have a very good reason to believe that MBTI is the answer, but I thought I would write this post because I thought it was interesting that (at least in its purest form) it attempts to answer that question of what is the cognition beyond what someone can answer on a test. Anyway, I'm sure I'll go check out the HEXACO test at some point. I will go back to my affirmation of "I do not limit my horizons". My goal with this post was to see if the MBTI could actually answer some of these cognition questions that a test really can't answer. I don't think we should give up on this area of research of looking into the true nature of cognition until we have better models that go beyond just what people answer to a number of different questions on a test. Either that or find how we can adapt our current best models (eg. HEXACO, Big Five, etc.) to be able to determine traits themselves not just people's self-reports; that would certainly be a bit of an improvement. Anyway, do you agree that a paradigm shift is required in psychology to be able to answer those deeper questions of psychology of how do you think not what you think, or do you think that our current methods already do that?

Also, I wanted to mention that the title maybe oversells the article a bit. The only thing I meant to argue in this article is that self-report personality tests are limited in the information they can provide.

I was talking to https://www.lesswrong.com/users/dmitrii-zelenskii-1 via DM. I think I uncovered there are a few main hypotheses that the MBTI has to prove:

1) The eight cognitive functions that the MBTI devises must be a division of distinct things that the brain does.

2) The eight cognitive functions that the MBTI devises have validity in terms of describing cognition.

3) Different people prioritize the different cognitive functions in different orders.

Which do you think is the most controversial hypothesis of these three?

If my hypothesis was that people think in terms of the MBTI cognitive functions and different people prioritize different cognitive functions, what could my null/alternate hypotheses be?

I think the biggest issue that the MBTI faces is that the test is so inaccurate that it puts people off the whole theory. Also with data, we could not only convince ourselves of the existing theory but we would be testing to see does it hold up in practice and maybe we could even subdivide or combine parts that right now are separate.