Drawing upon Jungian theory, Isabel Myers proposed that for each personality type, the cognitive functions (sensing, intuition, thinking, and feeling) form a hierarchy. This hierarchy represents the person's so-called default pattern of behavior.
The Dominant function is the personality type's preferred role, the one they feel most comfortable with. The secondary Auxiliary function serves to support and expand on the Dominant function. If the Dominant is an information gathering function (sensing or intuition), the Auxiliary is a decision making function (thinking or feeling), and vice versa. The Tertiary function is less developed than the Dominant and Auxiliary, but it matures over time, rounding out the person's abilities. The Inferior function is the personality type's Achilles' heel. This is the function they are least comfortable with. Like the Tertiary, the Inferior function strengthens with maturity.
Jung and Myers considered the attitude of the Auxiliary, Tertiary, and Inferior functions to be the opposite of the Dominant. In this interpretation, if the Dominant function is extraverted, then the other three are introverted, and vice versa. However, many modern practitioners hold that the attitude of the Tertiary function is the same as the Dominant. Using the more modern interpretation, the cognitive functions of the INTP are as follows:
Dominant: Introverted thinking (Ti)
Ti seeks precision, such as the exact word to express an idea. It notices the minute distinctions that define the essence of things, then analyzes and classifies them. Ti examines all sides of an issue, looking to solve problems while minimizing effort and risk. It uses models to root out logical inconsistency. Ti is calm, articulate, and aware of the forces that bind reality together. As introverted Thinkers, INTPs spend the majority of their time and energy ordering the interior, logical world of principles and generalizations in an effort to understand.
 Auxiliary: Extraverted intuition (Ne)
Ne finds and interprets hidden meanings, using “what if” questions to explore alternatives, allowing multiple possibilities to coexist. This imaginative play weaves together insights and experiences from various sources to form a new whole, which can then become a catalyst to action. Ne gives INTPs a grasp of the patterns of the world around them. They use their intuition to amalgamate empirical data into coherent pictures, from which they can derive universal principles. INTPs frequently puzzle over a problem for hours on end, until the answer suddenly crystallizes in a flash of insight.
 Tertiary: Introverted sensing (Si)
Si collects data in the present moment and compares it with past experiences, a process that sometimes evokes the feelings associated with memory, as if the subject were reliving it. Seeking to protect what is familiar, Si draws upon history to form goals and expectations about what will happen in the future. Si gives INTPs the potential for keen observation. They use this function to gather empirical data, use physical tools, perceive physical relationships, and support their internal logic with a rich sense of space.
 Inferior: Extraverted feeling (Fe)
Fe seeks social connections and creates harmonious interactions through polite, considerate, and appropriate behavior. Fe responds to the explicit (and implicit) wants of others, and may even create an internal conflict between the subject’s own needs and the desire to meet the needs of others. Fe drives the INTP to desire harmony in community. At their most relaxed, INTPs can be charming and outgoing among friends, or when they have a clearly defined role in the group. When under stress, however, INTPs can feel disconnected from the people around them, unable to use their extraverted Feeling to reach out to others. As their inferior function, Feeling can be a weak point; when threatened they will hide behind a wall of stoic logic. This can lead them to bottle up their emotions to preserve reason and harmony; but a failure to deal with these concealed emotions can lead to inappropriate outbursts.