If individuals used the dominant function all the time, they would be one-sided, always taking in information (and never making decisions) or always rushing to decisions (and not stopping to take in information). Therefore, there is a second-preferred function called the auxiliary function.
The auxiliary can be thought of as the first mate on the ship where the captain is the dominant function. The auxiliary function tends to develop after the dominant function. During adolescence and early adulthood, individuals come to develop skills in and rely on their dominant and auxiliary functions. They give less attention to the opposite functions, the letters that do not appear in their type.
It is critical to understand that the basis for good type development is a well-developed auxiliary function that can support the dominant function.
How does the auxiliary balance the dominant function?
If a person were always gathering information, he or she would be blown around like a small boat with an oversized sail and a small keeldriven by any change in wind direction. Such a person would be constantly drawn by new perceptions (whether Sensing or Intuition) but have difficulty making decisions or coming to conclusions. The auxiliary brings the person's focus to decisions.
In contrast, if a person were all judgment, he or she would be like a boat with a very large keel and a small sailvery sure and stable, but not open to new input from the wind. Such a person would be sure of his or her decisions (whether using Thinking or Feeling), but would be unable to take in needed new information to modify his or her behavior as conditions changed. The auxiliary brings the person's focus to information.
Dominant Intuitive types, for example, have Thinking or Feeling as their auxiliary function. If they prefer Feeling, then we would typically find that the Feeling function developed next in their lives after Intuition. They would still give the most weight to their Intuitive perceptions, but then they would make use of Feeling to reason and to make decisions about the intuitive information they took in.
Everyone needs to be able to pay attention to the outer world and move into action, and everyone needs to be able to pause for reflection and pay attention to their inner world. Extraverts need to be able to turn to their inner world at times and Introverts need to be able to turn to the outer world at times. The auxiliary function helps in this balancing act.
As you saw before, if you are an Extravert, you use your dominant function in the outside world. For balance, you use your auxiliary function in the inner world. The outer world is of more importance to you, but your auxiliary is there when you need to be involved in your inner world. Without using the auxiliary, an Extravert would never stop to reflect.
If you are an Introvert, you use your dominant function in your inner world. For balance, you use your auxiliary function in the outer world. The inner world is of more interest to you, but your auxiliary is there when you need to be involved in the outer world. Without using the auxiliary, an Introvert might never move into action.
The auxiliary function provides needed Introversion for Extraverts, and needed Extraversion for Introverts.
The dominant and auxiliary are the two middle letters of your four-letter type. They are sometimes called your function pair.
Excerpted from Building People, Building Programs
by Gordon Lawrence and Charles Martin (CAPT 2001)