ISTJ Functions

Mental functions are best described as ways we all use to perceive information and make decisions. Every person of any personality type uses all eight mental functions but depending on their personality type they'll use them in very different ways. The following describes how each of the eight functions plays a part in the ISTJ personality:

The first four functions are most relevant to how your personality type works.

Wheelhouse Functions

The first two functions are like a ship's wheelhouse in that they mostly direct or highly influence the rest of the functions' activities. We tend to identify the most with our Wheelhouse Functions as 'who we are'. For an ISTJ the wheelhouse functions are:

  1. Introverted Sensing (Si) focuses on memory, precedence and repetitive proof. It is most primary for the ISTJ personality. It is the captain of the ISTJs functional ship. Si is what gives the ISTJ personality that traditional bent, the desire to stay rooted in the past, and to enjoy repetitive tasks that reaffirm what works. It also gives ISTJs the gift of specialization through the use of rote memorization. For many ISTJs it gives them the ability to remember details of the past in a way that surpasses other personalities. Si is a perceiving function so it guides the way an ISTJ perceives the world more than any other function. To fully understand what it means to be an ISTJ, it's especially important to learn more about Introverted Sensing.
  2. Extraverted Thinking (Te) focuses on objective logic. It is the next most important function-attitude for the ISTJ personality. It's like the first mate of the functional ship. Their secondary Te is why ISTJ types tend to be logical and linear in their decision making. Te helps ISTJ types act and think efficiently with an eye toward achieving objectives that help satisfy their Si perceptions. Learning more about Extraverted Thinking is important to understand how ISTJs makes decisions.

Completing/Competing Functions

The second two functions are less conscious than our wheelhouse functions and can be somewhat problematic to the first two. They provide opposing ways of both making decisions and perceiving so they can show up in our consciousness kind of like devil's advocates. For an ISTJ the competing/completing functions are:

  1. Introverted Feeling (Fi) focuses on one's own feelings and values. It is the third function for ISTJs. The third function is often characterized by ambivalence. One might find it enjoyable and useful, but it can also be overtaxed quite easily and is not valued as highly as Si and Te for the ISTJ.  #2 Te and #3 Fi are both deciding functions but they offer completely opposed ways of deciding.  When there's a conflict, an ISTJ will tend to suppress #3 Fi in favor of their preferred #4 Te. With all this being said, #3 Fi values can play an important back up role in ISTJ decision making. Learn more about Introverted Feeling.
  2. Extraverted Intuition (Ne) focuses on possibilities in the outside world. It is the fourth function for ISTJs. #4 Ne is a completely opposite way of perceiving compared to #1 Si which focuses on tried and true ways of doing things. This often makes #4 Ne antagonistic for ISTJ users. #4 Ne can feel very fearful and insecure. For this reason, the fourth function is often called the Inferior Function. There is also an innate desire to master one's fourth function, so at the same time that #4 Ne is antagonistic and inferior, it is also aspirational.  There can be frequent inner conflict between #1 Si and #4 Ne for an ISTJ. The inner conflict might be something like, "I should be more open minded to possibilities and surprises, but that scares me, I need to control them in order to feel safe. It's better stay with the tried and true, but I also know that limits me."  Learn more about Extraverted Intuition.

Working with the First Four ISTJ Functions

Even as our third and fourth oppose our first two wheelhouse functions, they also provide important and completing ways for us to decide and perceive. When we are able to use all four together we tend to feel a significant sense of accomplishment and growth. For an ISTJ using all four might look something like this:

  1. Start with Si: What is the precedent? What has been done in the past and how specifically has it been done?
  2. Follow with Te: How can we meet our objective logically and efficiently? Sometimes the process stops here with Te and goes no further. However, Si and Te aren't able to process every decision to one's satisfaction.
  3. Back up with Fi: What are my personal values about this? How does this help humanity? What's most important to me here?
  4. Make it fail safe with Ne: What are the possibilities? What could go wrong here?

Unconscious Functions

Most personality systems focus solely on the first four functions. This is a good idea for simplicity's sake, however the truth is we all use all eight functions. The last four functions are often called the unconscious functions because they can remain largely unconscious and seem relatively superfluous to the user. But they are still useful for us and play important roles in our development.

Corresponding/Critiquing Functions

The next two functions are interesting because they are the same as the ISTJ wheelhouse functions but with different introversion/extraversion attitudes. Just as they are similar to the first two wheelhouse functions, they also provide a critique to them. For an ISTJ the critical/similar functions are:

  1. Extraverted Sensing (Se) uses a very different way of sensing than #1 Si. Though both #1 Si and #5 Se are detail oriented and concrete the critique each other: #5 Se focuses on the five senses here and now. It tends to be spontaneous and tactical in nature, and values immediate, novel sensory stimulus, excitement and adrenaline. This is directly opposed to the #1 Si norm of sticking with the tried and true and working with routine. #5 Se can also be a lot of fun. One way for ISTJs to enjoy Se is to find a way to enjoy it that is also reliable and repeatable. For instance, going on a bike ride every Wednesday can provide the sensory thrill of #5 Se with the predictability of #1 Si. Another way for ISTJs to use #5 Se is to plan thoroughly for it. Eliminating unwanted surprises and having the chance to fully internalize the experience before doing it can help. For instance, sky diving could provide a great #5 Se thrill, and planning thoroughly for it may give enough #1 Si stability to the experience that it becomes thoroughly enjoyable rather than stressful and overtaxing.
  2. Introverted Thinking (Ti) focuses on logic but in a different way than #2 Te. #6 Ti is more subjective. It is focused on systems, troubleshooting and figuring out how things work whereas #2 Te, favored by ISTJs is more linear and is geared toward project completion. #2 Te and #6 Ti critique each other: #6 Ti leans back and analyzes the situation as a whole to find the very best and ideal solution while #2 Te moves forward to find sufficient and efficient solutions. #6 Ti is especially useful before a project is executed in the "what could go wrong?" phase.

Collaborating/Clueless Functions

We can easily forget that the 7th and 8th functions exist altogether. Many times they operate underneath our awareness, but we can also employ them consciously to achieve important objectives because they can work in tandem with our first and second functions. For the ISTJ the Collaborating/Clueless functions are:

  1. Extraverted Feeling (Fe) focuses on other people's needs, social harmony, and morale. For the ISTJ, Fe can seem superfluous because Te is the way they most naturally deal with the outside world. Many ISTJs figure out that they can use their Fe to get things done more efficiently. After all, if morale is low it's hard to get things done. Gradually they might realize that Te and Fe work together with their Si. They can utilize their impressions of the past, and their knack for routine to become socially adept and improve morale. This helps them become a more well rounded and integrated person. Learn more about Extraverted Feeling.
  2. Introverted Intuition (Ni) focuses on underlying meanings and is future oriented. #8 Ni can seem like the most superfluous function of all for many ISTJ types. For the ISTJ underlying meanings typically come from past impressions, and looking at the past is the best way to determine what will happen in the future. However, #8 Ni can also work together with #2 Te to create a different viewpoint for accomplishing #2 Te objectives. Learn more about Introverted Intuition.