The auxiliary function occupies a pivotal position in Jungian typological theory, serving as the indispensable complement to the dominant or superior function in the architecture of conscious personality. The depth-psychology corpus treats this concept with considerable precision: Jung's original formulation in Psychological Types holds that the auxiliary must be 'in every respect different from the nature of the primary function,' a claim that subsequent commentators have interpreted in divergent ways. The most consequential dispute concerns attitude: Jo Wheelwright concluded that superior and auxiliary share the same introversion or extraversion, while Isabel Briggs Myers argued they must differ in attitude, a position that became foundational for MBTI practice. Beebe extends this architecture further, assigning archetypal roles to each function-position and elaborating the auxiliary as a 'parental' second function distinct in both type and relational quality from the heroic dominant. Samuels, offering a critical overview, notes that the auxiliary must derive from the opposite pair — rational or irrational — to the superior. Quenk's clinical work traces how differential development between dominant and auxiliary produces observable personality dynamics under stress. What unites these voices is recognition that the auxiliary is neither merely derivative nor fully conscious, but constitutes the essential second axis of type differentiation around which the remaining function-attitudes orient themselves.
besides the conscious, primary function there is a relatively unconscious, auxiliary function which is in every respect different from the nature of the primary function
Beebe cites Jung's foundational rule that the auxiliary function must differ entirely in nature from the dominant, and traces how the sixteen type profiles emerge from just these two differentiations.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017thesis
a person will have a primary (or superior) mode of functioning... The person will not depend exclusively on this superior function but will utilise a second, or auxiliary function as well. This, according to Jung's observations, will come from the opposite pair of rational or irrational functions
Samuels articulates the structural rule that the auxiliary function must be drawn from the opposite rational or irrational pair to the superior function, grounding the model's internal balance.
, Jung and the Post-Jungians, 1985thesis
Isabel Briggs Myers... took Jung's subsequent statement, that the auxiliary function is 'in every respect different from the nature of the primary function', to mean that the auxiliary must differ from the superior function in attitude
This passage maps the central interpretive split between Wheelwright and Myers regarding whether the auxiliary must differ from the superior in attitude, and notes Jung's own relative indifference to the distinction.
, The Handbook of Jungian Psychology: Theory, Practice and Applications, 2006thesis
the differentiation of a strong natural superior and accompanying auxiliary function that is different in every respect is the starting point for further differentiation. The other function-attitudes operate largely out of awareness until and unless they become conscious
Beebe establishes that the superior-auxiliary pair constitutes the foundational axis of type development, with all remaining function-attitudes remaining substantially unconscious until individuation proceeds.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017thesis
The model asserts, with Jung and subsequent Jungians, that if the superior function is irrational the auxiliary will be rational, and vice versa. It agrees with Myers and the MBTI counselors that if the superior function is introverted the auxiliary will be extraverted and vice versa.
Beebe's eight-function model explicitly codifies the complementarity rules governing auxiliary function attitude and type, integrating Jungian and Myers traditions.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017thesis
For ISTJ, therefore, Sensing that is introverted (commonly referred to as Introverted Sensing) is the dominant function. The auxiliary function is identified by the remaining middle letter, T, which has an 'e' next to it.
Quenk demonstrates the practical MBTI procedure for identifying the auxiliary function from the four-letter type code, grounding theory in assessment practice.
, Was That Really Me? How Everyday Stress Brings Out Our Hidden Personality, 2002supporting
your auxiliary Introverted Feeling will be expressed less often and with less confidence and facility. And you may have developed only some of the attributes associated with a preference for Introverted Feeling
Quenk distinguishes the differential development between dominant and auxiliary, noting that the auxiliary is used with less frequency, confidence, and completeness than the dominant function.
, Was That Really Me? How Everyday Stress Brings Out Our Hidden Personality, 2002supporting
It's my parental second function I must use when taking care of others, not my heroic first function, and that means I take the best care of people not when I heroically show them a possibility they haven't thought of, but when I help them to define more sharply what they already know.
Beebe illustrates his archetypal assignment of the auxiliary as a 'parental' function through autobiographical reflection, distinguishing its caregiving quality from the heroic dominant.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017supporting
of auxiliary and tertiary functions 138–141; of superior and inferior functions 128–33; see also demonic/daimonic personality, opposing personality, trickster, witch/senex
Beebe's index entry confirms that the auxiliary and tertiary functions each have shadow counterparts and distinct archetypal roles within the full eight-function model.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017supporting
when thinking is the second of the two leading functions, feeling (its opposite on the same axis of 'rational' functions) will be tertiary, and that, when intuition leads, sensation (intuition's opposite on the axis of 'irrational' functions) is going to be the inferior function
Beebe uses autobiographical type analysis to illustrate how the position of thinking as auxiliary determines the placement of all remaining functions, demonstrating the structural logic of the four-function axis.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017supporting
ENTP: auxiliary function of, 258... tertiary function of, 246
An index entry confirming that Quenk systematically treats each type's auxiliary function within her clinical typological profiles.
, Was That Really Me? How Everyday Stress Brings Out Our Hidden Personality, 2002aside
these particular roles, centered as they are on the qualities of the superior and inferior functions, help to define the 'spine' of personality
Beebe notes that the superior-inferior axis forms the personality's spine, situating the auxiliary function as part of the broader archetypal structure of type rather than its defining axis.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017aside