TL;DR: MBTI borrows from Carl Jung two attitudes, introversion and extraversion, and four functions, thinking, feeling, sensation and intuition, set out in Psychological Types (1921). Myers and Briggs added the J/P axis, combined it into sixteen types and turned the theory into a self-report questionnaire. Psychometric research finds MBTI weak on reliability and validity, so it should not be used to draw firm conclusions about people or careers.
What Does MBTI Borrow from Carl Jung, and Where Does It Differ?
MBTI borrows from Carl Jung two attitudes, introversion and extraversion, and four psychological functions, but adds the J/P axis, combines them into sixteen types and turns the theory into a self-report questionnaire. The biggest difference lies in purpose: Jung described tendencies in order to understand individuation, while Myers and Briggs created a classification tool for use in daily life, education and work.
What Did Carl Jung Set Out in Psychological Types?
Jung published Psychologische Typen in 1921; H. Godwin Baynes's English version appeared in 1923 under the title Psychological Types, or the Psychology of Individuation[1]. In this work Jung sets out two basic attitudes of the mind, extraversion and introversion, together with four psychological functions: thinking, feeling, sensation and intuition[1]. He divides the four functions into two opposing pairs, thinking against feeling and sensation against intuition, and calls thinking and feeling rational functions and sensation and intuition irrational functions[1].
This structure yields eight types: four extraverted and four introverted, each tied to a dominant function. Jung also speaks of an auxiliary function and of the least developed function lying in the unconscious, making the system dynamic rather than four fixed boxes[1].
What Do Jung's Two Attitudes, Introversion and Extraversion, Mean?
For Jung, extraversion is the tendency to direct psychic energy toward the outer world, toward objects, events and other people; introversion is the tendency to direct it toward the inner subjective world[1]. These are two poles of one axis, not two absolute kinds of person. Each person has a dominant attitude, while the other exists at the unconscious level and may surface when the individual is unbalanced[1].
What matters is that Jung does not use these two attitudes to label "introverts" or "extraverts" in the everyday sense. He uses them to describe how a psychological function operates: the same thinking function can be extraverted or introverted, producing two very different character types[1].
What Are the Four Psychological Functions in Psychological Types?
Jung's four functions are thinking, feeling, sensation and intuition[1]. Thinking and feeling are two ways of evaluating, of judging; sensation and intuition are two ways of taking in information. Each person has one dominant function, one auxiliary function, and two functions at a lower level[1].
| Function | Pair | How it operates according to Jung |
|---|---|---|
| Thinking | Rational | Analysis, logic, seeking laws and systems |
| Feeling | Rational | Evaluating by values, likes and dislikes |
| Sensation | Irrational | Receiving concrete data through the senses |
| Intuition | Irrational | Grasping possibilities and meanings hidden behind events |
The table above is Nhật Nguyệt's interpretation based on Jung's description in Psychological Types[1]. Note that Jung uses "feeling" in the sense of a function that evaluates value, not the same as "emotion" in everyday Vietnamese. He also does not treat the four functions as four fixed "types" of person, but as four ways the mind can operate[1].
What Did Myers and Briggs Add to Jung's Theory?
Katharine Briggs and Isabel Myers drew on Psychological Types to build the MBTI questionnaire, added a fourth axis, J/P (Judging/Perceiving), and combined the four axes into sixteen types. The J/P axis describes how a person approaches the outer world: preferring judgment (J) or preferring perception (P). In Jung's theory there is no such axis as an independent dimension[1].
Myers and Briggs also turned the theory into a self-report questionnaire that can be scored and used for classification. This was the turning point compared with Jung: from a theory describing psychological processes, MBTI became a measurable tool that could be used widely.
Where Does MBTI Differ from Jung?
MBTI differs from Jung in four main points: it adds the J/P axis, turns tendencies into fixed types, moves from clinical observation to a self-report questionnaire, and aims at practical application rather than describing individuation.
- Added J/P axis: Jung has no such dimension; Myers and Briggs added it to distinguish how people live outwardly.
- Sixteen types instead of eight: Jung describes eight types based on attitude and dominant function; MBTI combines four binary axes to give sixteen types.
- Self-report questionnaire instead of observation: Jung worked with patients and cultural material; MBTI uses self-reported questions and is scored.
- Applied purpose: Jung aimed to understand the unconscious and individuation; Myers and Briggs aimed at use in education, careers and relationships.
This difference does not mean MBTI is "wrong" compared with Jung, but that the two products serve two different purposes. Still, the distinction must be kept clear: Psychological Types is a theory, not a measurement result[1].
How Does Psychological Research Rate MBTI's Reliability?
Psychometric reviews point to limits in MBTI's reliability, validity and norms. Gregory J. Boyle (1995), in an article in the Australian Psychologist, reviewed these limits and did not recommend routine use of MBTI, advising psychologists to be cautious[2]. This is a peer-reviewed article, level A evidence within the scope of this article.
Specifically, Boyle raises issues of reliability (results may change between sittings), validity (whether the tool measures what it claims to measure) and norms (which reference group it is compared with)[2]. These limits do not deny MBTI's value as reference, but they call for caution when using it to make important decisions about people.
Should MBTI Be Used to Understand Yourself and Choose a Career?
MBTI can be used as a reference tool to prompt thinking about oneself, but it should not be used to draw firm conclusions about personality, ability or career. Boyle (1995) does not recommend routine use of MBTI because of its psychometric limits[2]. This means: if you find MBTI descriptions useful, treat them as a lens, not a verdict.
For Jung, a psychological type is a tendency that can change with personal development, not a fixed box for sorting people[1]. So neither Jung nor psychometric research supports using one MBTI result to decide a career or judge others.
Nhật Nguyệt's Suggestion
When reading about MBTI, keep three layers apart: Jung's original theory, the MBTI tool of Myers and Briggs, and the psychometric evidence about that tool. Each layer has its own value, but they should not be merged into a single claim about a person. If you are interested in Jung, read Psychological Types directly or in scholarly translations; if you are interested in MBTI, know that the tool has limits recorded in psychological research[2].
