This month, Vladimir Costescu has requested (with dollars):

For this month’s funded post, I’d like to see you write about personality typing, with an emphasis on Myers-Briggs / Jungian typology. This means I’d like to see you write mostly about MBTI and dig a bit into cognitive stack theory, but if you happen to have tidbits of knowledge about other methodologies (e.g. Big Five, Enneagram, etc.) already in your mental data banks, it would be cool to hear about them too.

Don’t worry: I don’t know anything about cognitive stack theory, or even what that means. But that’s never stopped me before!

The things I do know

Well, I know that everyone on the Internet is an INTP.

At first blush, “personality type” assessments look like the same flavor of thing as horoscopes — everyone is one of this dozen-odd kinds of people, here’s how they interact, here’s an Internet quiz to tell you which one you are. seems telling that you already mentioned several different personality categorizations.

On the other hand, certainly some people act differently and some people act similarly, so there oughta be some kind of way to draw lines. But I know I have a tendency to want to categorize everything, so I have to wonder: is this any more useful than horoscopes in practice? I don’t know.

Myers–Briggs at least uses a combination of multiple factors, rather than singular broad-stroke categories like “you are a Capricorn”. Alas, they’re all binary, with no room for a middle ground or “it’s situational”. I’m sure everyone is familiar with the Forer effect, where a classroom of students were all given the same fake “personality sketch” and all of them thought it was very accurate. One of my takeaways from that was that few people perceive themselves as living on extremes — the vague fake profile seemed to fit everyone because it spoke of “at times” and “certain amount” and “some”.

Really, I don’t see why we need any more than the original personality types.

The things I sort of know

I only know what some of those listed things mean, so that’s a good place to start.

Myers–Briggs (Type Indicator), of course, refers to a very well-known system of personality typing that identifies types with four letters, like INTP. Each letter is chosen from a pair, so there are sixteen possible combinations, thus sixteen distinct personality types.

Jungian typology is the original form of that idea, developed by Carl Jung. Jung proposed four main psychological “functions”, in two pairs. Sensation and intuition are “perceiving” functions. Thinking and feeling are “judging” functions. His idea was that, while everyone relies on all four functions, everyone also prefers them in some order, with one in particular being dominant. (There are a lot of comparisons to left- vs right-handedness.) Additionally, everyone approaches the world with one of two attitudes: introversion or extraversion. So that’s eight possible personality types. I’ve also pieced together that he may have ascribed two dominant functions to people, one for conscious behavior and one for unconscious behavior, which gives us a total of thirty-two.

Apparently Jung invented the notions of “introversion” and “extraversion” (his spelling), though his intent was to describe interactions with the world as a whole, rather than a shallow dichotomy of “likes to party” vs “likes to stay at home”. In this sense, introversion means turning one’s attention inwards (look at all that Latin coming in handy) to think and reflect and ponder, whereas extraversion means turning one’s attention outwards to interact and observe and act. Obviously everyone does some of both, but most of us lean more strongly towards one, and have to put active effort into doing the other.

You might also say that introversion is about depth, whereas extraversion is about breadth.

While Jung proposed that everyone prefers the four functions in some order, his list of only eight types fails to mention the second-most preferred (“auxiliary”) function. He asserted that the least-preferred function was always the counterpart of the dominant function, which means the second and third functions must also make a pair… but that still leaves the identity of the second function ambiguous.

In a way, MBTI was designed to address this. Which is a thing I didn’t know! The types are always presented as though all four axes are independent, but that’s not the case. The axes are:

• Introversion (I) versus extraversion (E), with the same meanings as with Jung.

• Sensing (S) versus intuition (N) indicates which of the “perceiving” functions is preferred. Sensing relies on objective, concrete observation; intuition is interested in imagination, extrapolation, and finding patterns.

• Thinking (T) versus feeling (F) indicates which of the “judging” functions is preferred, where “judging” here refers to making decisions in general. Thinking relies on logical reasoning, rules, and truth; feeling is about empathy, consensus, and weighing context.

• Perceiving (P) versus judging (J) indicates which of the above two functions is preferred! And it indicates which is preferred when interacting with the world — so it indicates the dominant function for extraverts, but the auxiliary function for introverts. So it ties the other three things together.

Thus, the curiously popular diagnosis of INTP actually means (in Jungian terms) that someone is an introverted thinker whose auxiliary function is intuition.

In other words you could express these types with only three letters, an improvement of 25%.

The things I don't know

Cognitive stack theory is I don’t know. This doesn’t seem to be a well-known phrase. I think it refers to the idea that everyone expresses each of Jung’s eight types (4 functions × 2 attitudes) to some degree, and in some order. I found a page explaining that INFJ has a “stack” of:

1. Introverted intuition
2. Extraverted feeling
3. Introverted thinking
4. Extraverted sensing

Which matches up with the description of MBTI above — J means F is preferred when extraverted, so it goes second, meaning the N is first and is introverted, and then the other two are just opposites.

I’m not really sure where this idea came from, and I can’t find much about it besides a couple Reddit threads and a website that desperately wants to sell me some books all conspicuously written by the same author. Honestly this just sounds like some INTP people latched onto a neat system of putting people in boxes and found a way to add even more boxes. And sell books about it.

Moving right along…

Big Five is interesting. It’s a multi-axis measurement as well, but the axes don’t seem to be emphasized as being quite so binary. There are five (surprise) axes, conveniently spelling out OCEAN. I’m basically copying this from Wikipedia now oh well:

• Openness to experience ranges from curious to cautious
• Conscientiousness ranges from organized to careless (carefree?)
• Extraversion ranges from outgoing to reserved
• Agreeableness ranges from compassionate to detached
• Neuroticism ranges from nervous to confident

One thing definitely stands out to me here: these are common ways you might describe other people, whereas MBTI is a more analytical measurement of what (presumably) goes on inside your own head. So in a way, this seems a lot more objective! It’s just some common descriptions of people’s behavior. Explaining someone else’s personality is easy, whereas with MBTI you’d either have to guess wildly or get them to take a personality test.

There seem to be more details to this, but they rapidly fizzle off into obscurity, which is not a particularly good sign.

Enneagram is some kind of spiritually-inspired thing that gives me instant “new age” heebie-jeebies, and also divides people into nine categories. They’re more like archetypes, really: reformer, helper, achiever, individualist, loyalist, enthusiast, challenger, and peacemaker. There are some seven-odd traits available to each archetype, making this vague enough that you could probably fit yourself to any of them if you squinted a bit.

Oh I’m out of things I don’t know.

Other things I sort of know

I’ve had a look for other major typologies, but MBTI is the most popular by a ridiculous margin.

There’s the “Type A” versus “Type B” thing. In practice it seems to reduce to just “Type A”, because I’ve never once heard anyone refer to themselves or anyone else as having a “Type B personality”, and I actually wasn’t sure how many lettered types there were supposed to be. Maybe Type B people are the kinds of people who don’t care what type of personality they have.

Apparently this dichotomy was invented by two cardiologists, because they observed in a study that Type A people were more likely to develop heart disease. This was over 50 years ago now, though, so I have no idea how it leaked into popular culture when it was only ever meant as a link to heart disease, and apparently it’s not even a good one.

I found a few more, but I’ve never heard of any of them before, despite the recurring claim that they are “widely used” or “the most popular” or whatever. I suspect more people are trying to sell their books.

What was I supposed to be talking about again

Which I guess brings me back to that horoscope comparison. It’s cute and it’s fun and it’s entertaining, and that’s why it’s now a billion-dollar industry.

But I’m still unclear on what the point is, scientifically. MBTI in particular came out of actual psychology, and I understand wanting to figure out how personality works, but I don’t know what it’s supposed to predict — and the goal of science is to make predictions. (Actual ones. Like “if I let go of this, it will fall”.) What do personality types predict? I can’t tell. From the sounds of it, your personality type doesn’t even very reliably predict what result you’ll get next time you take the same personality test.

It’s definitely nice to put things in boxes, and I know I’m particularly attracted to it. (I know this because I’m an INTP and that’s what we do.) But over the last few years I’ve seen boxes wreak havoc, so I’m trying to resist the urge to categorize that which doesn’t need categorizing.

Boxes are convenient, but limiting. Once we have a set of boxes, we become accustomed to them, generalize about them, forget they’re a mere convenience, and start to expect the world to conform to our boxes. When something doesn’t fit in our boxes, we get confused or uncomfortable or even angry. We squabble, we insult, we get mean, we pass laws, we go to war, all the while forgetting that we’re up in arms about categories we completely made up in the first place.

So while it’s interesting to see how different people have decided to categorize human personality, I’m really wary of using it for anything more than its entertainment value. I’ve run across anecdotes that personality types are used for career guidance (?), making employment decisions (!), and relationship counseling (?!) — but in all of those cases, a personality type is just a poor proxy for the questions you could and should be asking.

Which is why I see “I’m an INTP”, I hear: “I prefer to direct my energy inward to reason logically about problems, and relate most strongly to the external world by looking for patterns, which is why I think it’s reasonable to express everything about me as a person with just four letters.”