3 min read

How to Type Someone

A brief guide on how to find someone's MBTI type and verify your answer
Prompted by this thread from [[Malcolm Ocean]]. This post is a WIP, DM me if there's anything I can explain/talk more about

This post is for readers who...

  • understand what the Jungian cognitive functions are
  • who want to be be confident while typing without relying on "feelings/vibes"or the result of online personality tests.

If you want to learn the basics, check out these posts and videos -
- Type Fundamentals Guide @mbti-notes
- The Principles of Cognitive Function Theory @mbti-notes

I particularly like this video because it likens cognitive functions to colors, which is an apt analogy, since people, like colors, "lie on a spectrum"

Of course, memes help too.

I verify by checking for congruence between the different "laws" of cognitive functions.


  1. Identify the dominant function.
    • This is the easiest to tell, since they'll use it all the time. Once you know this, you also know the person's inferior function. This narrows it down to two options.
  1. Check for their Blindspot/PoLR/Trickster function.
    • This is the opposite of their 3rd function. (E.g. for an ENTP with NeTiFeSi, it's Fi)
    • This is the function will present their most obvious weaknesses, their blindspot.
This video is great to learn about how each type's blindspot affects them
  1. Check for their "critical parent" function.
    • This is the mirror of their 2nd function. (E.g. for an ENTP with NeTiFeSi, it's Te).
    • Types will often use this function "in anger", and do so poorly.
    • And often they will openly despise other people who don't use this critical function well, or at the very least, find it hard to respectfully interact with someone who's weak in the area over a long-term.
      • It's like saying, "what is an instant red flag for you?", or, "what do you tend to be cynical about?"
Video that explains critic function a bit

Extra - a little more nebulous

  1. Check if they have ever experienced the grip of their inferior function.
    • What this means is that during times of stress, the type will try to use their inferior function more than their dominant one.
      • Example
        • When the ENTP undergoes an Si grip, they'll seem a lot less creative, worry about their internal state of wellbeing and feel sick, or focus more/ be overwhelmed by details.
  1. Model their relationship dynamics and check if it matches reality.
    • If you have a large dataset of people they interact with and their types--one where you have multiple people of the same type-- you can check how their relationships align with the theory.

      • This WILL NOT work if you try to crosscheck with a small sample that might contain incompatible enneagram types or unhealthy, underdeveloped individuals.
  1. Check for cognitive function loops
  1. Check if their shadow/four sides of the mind match
    • I don't completely understand the shadow in cogfuncs terms, or what it is, but the four sides of the mind is a useful metric as you can see how people resemble these other types as they grow or under stress

A video from CS Joseph on the four sides of the mind

I wish I took a bit longer to flesh this out, but I've run out of motivation right now– Feel free to DM and ask for explanations, it might help me expand this post.

If I want to go beyond MBTI/Jungian functions, where should I look?

The Enneagram, its holy ideas, and instinctual variants.