Auxiliary Function According to Carl Jung

Posted on July 22nd, 2025 in Jungian Theory by Mara

The auxiliary function is actually somewhat controversial, which is partially what drove me to dedicate an article on it. However, it’s worth stating that Carl Jung actually says very little on the subject in his book, Psychological Types, hence why it is subject to such debate. I’m going to go over the section that he dedicated to the auxiliary function, and interpret it in the way I believe makes the most sense. Obviously, everyone is welcome to their own opinion.

Prerequisite Information

This article is actually the second in a series, the first being the Dominant Function According to Carl Jung. The first article lays the groundwork for some basic concepts that I may not cover quite as in depth in this article, so be sure to check it out if you haven’t already. To understand this article, it would also help to have a basic understanding of the cognitive function stack. The auxiliary function specifically is the second function in one’s cognitive function stack, preceded only by the dominant.

The Theories on the Auxiliary Function

I’m going to state up front that there are a couple of different competing theories on the auxiliary function. Myers-Briggs, for instance, defines the auxiliary as having the opposite orientation as the dominant. In other words, an INTP is Ti-Ne-Si-Fe, which you can see shows an introverted dominant function, and an extraverted auxiliary. However, many people believe that the auxiliary must possess the same orientation as the dominant. Often, if they’re adhering to the Myers-Briggs four-letter type codes, they’ll just rearrange an INTP’s stack to make the tertiary come second and the auxiliary go third. In other words, an INTP becomes Ti-Si-Ne-Fe. I’ll address this in my article below, and share what I think the text indicates.

Attributes of The Auxiliary Function

1. Less Differentiated

“Closer investigation shows with great regularity that, besides the most differentiated function, another, less differentiated function of secondary importance is invariably present in consciousness and exerts a co-determining influence.” – Psychological Types, Page 405

As mentioned in my article on the dominant function, differentiation is the development of a function’s distinctions, thus separating it from the rest of the functions. In the above quote, Jung points out that there is a secondary function that has an influence on the dominant. It is differentiated, but less differentiated than the dominant. In other words, it has been developed up out of the unconscious, but not to the same extent as the dominant.

2. Of Secondary Importance

“But since it is a vital condition for the conscious process of adaptation always to have clear and unambiguous aims, the presence of a second function of equal power is naturally ruled out. This other function, therefore, can have only a secondary importance, as has been found to be the case in practice.” – Psychological Types, Page 405

Of course, we know that the auxiliary function cannot be as differentiated as the dominant, because if it were to catch up to the dominant, the dominant could no longer be dominant. Jung essentially points out the need for a single, decisive function, else an individual would have no clear direction. There must be a clear leader (ie: the dominant function), but the auxiliary function will be its senior advisor.

3. Not Valid In Its Own Right

“Its secondary importance is due to the fact that it is not, like the primary function, valid in its own right as an absolutely reliable and decisive factor, but comes into play more as an auxiliary or complementary function.” – Psychological Types, Page 405

The auxiliary function will be a valuable function, but people will not see their auxiliary as completely reliable. Thus, when faced with critical decisions, people will rely on what they believe is most reliable. As a less reliable function, the auxiliary is not valid in its own right, but only valid when coupled with the dominant function. In other words, you might be able to imagine existing without your auxiliary function, but the same cannot be said about your dominant. The auxiliary only serves to complement the dominant.

4. Cannot Be Opposed To The Nature Of The Dominant

“Naturally only those functions can appear as auxiliary whose nature is not opposed to the dominant function. For instance, feeling can never act as the second function alongside thinking, because it is by its very nature too strongly opposed to thinking. Thinking, if it is to be real thinking and true to its own principle, must rigorously exclude feeling. This, of course, does not do away with the fact that there are individuals whose thinking and feeling are on the same level, both being of equal motive power for consciousness. But in these cases there is also no question of a differentiated type, but merely of relatively undeveloped thinking and feeling.” – Psychological Types, Page 405-406

Jung says elsewhere that differentiating one function will demand the suppression of it’s opposite. (This is the premise of inferior functions, that I won’t be directly discussing in this article.) In the above section of text, he applies this concept to the auxiliary function, explaining that the auxiliary function cannot be an opposite to the dominant, else it wouldn’t be differentiated enough to exert a strong secondary influence. (The dominant would have suppressed it). Therefore, the auxiliary has to be a different type of function altogether. So, a judging dominant (thinking or feeling) will have a perceiving auxiliary (intuition or sensing), and vice versa. Perceiving and judging complement each other, whereas two judging function or two perceiving functions would act in opposition to each other.

“Experience shows that the secondary function is always one whose nature is different from, though not antagonistic to, the primary function. Thus, thinking as the primary function can readily pair with intuition as the auxiliary, or indeed equally well with sensation, but, as already observed, never with feeling. Neither intuition nor sensation is antagonistic to thinking; they need not be absolutely excluded, for they are not of a nature equal and opposite to thinking, as feeling is—which, as a judging function, success-fully competes with thinking—but are functions of perception, affording welcome assistance to thought. But as soon as they reached the same level of differentiation as thinking, they would bring about a change of attitude which would contradict the whole trend of thinking.…Hence the auxiliary function is possible and useful only in so far as it serves the dominant function, without making any claim to the autonomy of its own principle.” – Psychological Types, Page 406

As stated, the process of differentiating a function like the dominant causes it to suppress anything that runs counter to its nature. Therefore, the auxiliary cannot be one whose nature would antagonize the dominant. However, if that were even possible, it would result in a function competing for control, and if it were to succeed, it would create a paradox. There can only be one dominant, or one primary driver. A competing auxiliary would water down the dominant, making it less differentiated, less effective, and not actually in complete control. For a function to truly be an auxiliary function, it must complement the dominant, else it’s not just useless but a hinderance.

5. Relatively Unconscious

“For all the types met with in practice, the rule holds good that besides the conscious, primary function there is a relatively unconscious, auxiliary function…” – Psychological Types, Page 406

The auxiliary function is “relatively unconscious”, which doesn’t mean that it’s unconscious, but that it’s less conscious than the dominant. It’s unconscious relative to the dominant, but not actually unconscious. (As I explained in the prior article, a function is conscious when it’s under conscious control, not just when it’s visible or identifiable to you. If you can’t consciously control it, it’s not conscious.) Jung spells this out clearly later, when giving examples of function combinations. For instance, he explains that conscious, practical thinking will correlate to having unconscious, intuitive-feeling (ie: high sensing and thinking with low feeling and intuition).

6. Different In Every Respect To The Nature Of The Dominant

“For all the types met with in practice, the rule holds good that 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.” – Psychological Types, Page 406

I’ve been keeping these sections and their quotes linear, or true to the order that they appeared in the book, for a reason. Jung makes the above statement after explaining how the auxiliary function cannot be antagonistic to the dominant. However, he really only says that the dominant’s opposite dichotomy cannot be auxiliary (e.g. thinking cannot have feeling). All other dichotomies are possible (e.g. thinking can have intuition or sensing, just not feeling). However, saying that the auxiliary function is “in every respect different” suggests that there are more ways it can be different then just the one, aforementioned way. It appears to be more than just a matter of judging versus perceiving. In my opinion, this indicates that it must also have a different attitude (ie: introversion or extraversion). In other words, introverted thinking can’t have introverted sensing as the auxiliary, but rather extraverted sensing.

Some Closing Thoughts

Jung didn’t develop this theory too deeply, which is why people are left guessing at some of the details. I’ve always preferred the idea that the auxiliary is of the opposite orientation, simply because that would create a more balanced, capable person. This is also why I don’t like the idea of jumpers or permanent loopers being a healthy, normal state. Balance is important.

Jung points out in an earlier chapter that he observed people shifting their attitude based on external factors, some for brief periods and some for more extended periods. For instance, he explains that an extravert living with an introvert may start to demonstrate introverted behavior until, as Jung puts it, the “alien influence is removed”. In my opinion, this marked shift in behavior suggests ready access to a function of the opposite orientation.

Reference Book:

Psychological Types (The Collected Works of C. G. Jung, Vol. 6) (Bollingen Series XX)

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