Guide To Understanding the Function Stack

Have you ever found yourself wondering how the cognitive function stack relates to the 4 letter type code? Granted, it’s not hard to find those tables that list off the function stack for each of the 16 types. It’s not hard to look up ISTP and see Ti-Se-Ni-Fe or ISFJ and see Si-Fe-Ti-Ne. But how does the type connect to the function stack? Doesn’t it seem a bit random? Well, in this article, I aim to explain how that function stack is built for each type. I was going through it the other day with a friend of mine, and realized it might be a source of confusion for others as well. I’m going to try to make this as clear and simple as possible. So, let’s get started.

Overview

We are all capable of achieving balance, and function theory accounts for that. What do I mean? Well, we each have a sensing function, an intuition function, a thinking function, and a feeling function. As we mature, we develop each of these four functions further, especially the lower ones, allowing us to hopefully achieve a healthy balance. After all, each is necessary for some facet of life.  Additionally, each person has two extraverted functions and two introverted functions, which means that we are each capable of acting like both an extravert and an introvert, if we develop our cognitive functions.

Laying the Ground Work

The Function Categories

The functions are broken up into two categories: judging and perceiving. The Judging functions are poorly named. Think of them more like the decision making functions. The Judging functions are the Feeling and Thinking functions. The Perceiving functions, on the other hand, refer to how we take in and process information. They are the Intuition and Sensing functions.

The J/P and I/E Dichotomies

Obviously, based on the information above, J/P and I/E are not functions, so what’s their purpose or what do they mean?

I/E is accounted for in the function stack by placing an I or E next to every function type. Meaning, the feeling functions are broken into Fi and Fe. Fi = introverted feeling. Fe = extraverted feeling. The same goes for N (Ne and Ni), S (Se and Si), and T (Te and Ti).

J/P determines what type of function you’ll prefer to extravert to the world. SO, a Judger (or a Je) will have an extraverted judging function within the top 2 functions of their stack. A Perceiver (or a Pe) will have an extraverted perceiving function within the top 2 functions of their stack. Basically, when someone looks at you and instinctively types you as a J, it’s because the function that you are displaying to the world is a J function (Te or Fe).

The Rules in Depth

Here is the basic information that you need to know, some of which is repeated from the section above and some of which may seem obvious, but I’m trying cover all bases.

1. Every type has 1 of each judging function (T and F) and 1 of each perceiving function (N and S). Ergo, we each have an N, S, T, and F function, which makes up the total stack of 4 functions.
2. Both judging functions cannot be the same orientation (meaning introverted or extraverted). The same applies to the perceiving functions. (IE: 1 judging function will be extraverted and 1 will be introverted)
3. Subsequently, this means that we each have 2 extraverted functions and 2 introverted functions.
4. The extraverted and introverted functions must alternate in the function stack (I,E,I,E or E,I,E,I)
5. An (I) will lead with an introverted function. An (E) will lead with an extraverted function.
6. Every type has a perceiving function (S or N) and a judging function (T or F) in their top 2 function spots, and these 2 will be your preferred functions
7. A P will have an extraverted perceiving function (Se or Ne) in their top two, and a J will have an extraverted judging function (Te or Fe) in their top 2

Some Shortcuts

1. P = Se or Ne in top 2
2. J = Te or Fe in top 2
3. SP= Se in top 2, NP= Ne in top 2
4. ESXP= Se in top spot, ENXP= Ne in top spot
5. ISXP= Se in second spot, INXP= Ne in second spot
6. TJ = Te in top 2, FJ = Fe in top 2
7. EXTJ= Te in top spot, EXFJ= Fe in top spot
8. IXTJ= Te in second spot, IXFJ= Fe in second spot

Building a Type’s Function Stack: ENTJ

Now that I’ve covered the basics, let me give you a couple of examples so you understand how to work out any type’s function stack.

ENTJ = ?-?-?-?

The first thing to notice from this type code is that ENTJs are extraverted, so the dominant (1st) function will be an extraverted function. The second thing to notice is that ENTJs are Judgers, ergo, they will have an extraverted judging function in their top two. of course, since we already stated that an ENTJ is extraverted, we now know that their dominant function must be the judging function. So what type of judging function do ENTJs prefer? If you look at the type code, you’ll see that they are Thinkers. Ergo, their preferred judging function will be Te.

ENTJ = Te-?-?-?

What next? Well, if you refer back to the rules, you know that the auxiliary (2nd) function has to be a perceiving function, since the main judging function has already been accounted for. So, what is the ENTJ’s preferred perceiving function? Looking at their 4 letter type code, you’ll see N. The rules also dictate that introverted and extraverted functions have to alternate, meaning that an ENTJ’s auxiliary function, by process of elimination, has to be Ni.

ENTJ = Te-Ni-?-?

This is where it gets easy. The rules state that we have one function from each category. Currently, our ENTJ stack is missing a sensing and feeling function. Since the rules also state that both perceiving functions (N and S) can’t be the same orientation or the same type, we know that the perceiving function must be Se. Using the same logic,  we can determine that the other judging function is Fi. So, now to order them. The rules state that introverted and extraverted functions must alternate, which only leaves us with one option: ENTJ = Te-Ni-Se-Fi

Building a Type’s Function Stack: INFP

Let me give you one more example.

INFP  = ?-?-?-?

INFPs are perceivers, so they will have an extraverted perceiving function (Ne or Se) in their top two functions. They’re also introverted so that extraverted perceiving function CANNOT be their dominant (1st) function, therefore it must be auxiliary (2nd). By looking at their 4 letter type code, we know that their preferred type of perception is Intuition. Ergo…

INFP  = ?-Ne-?-?

Next, we know that their dominant function (1st) must be a judging function (F or T), since the perceiving function in their top 2 has been accounted for. INFPs prefer Feeling, so their dominant must be Fi, since they’re introverts.

INFP = Fi-Ne-?-?

What’s missing? The two missing function types are T and S. The T must be extraverted, since the F is introverted. The S must be introverted since the N is extraverted. SO the two missing functions must be Te and Si. Introverted and extraverted functions must alternate, so what leaves us with INFP = Fi-Ne-Si-Te.

Conclusion

I hope that all makes sense. You should be able to apply the above logic to any 4 letter type code to determine their function stack. Let me know if you have any questions, or if something is unclear!