I have already covered the history of MBTI elsewhere on this site – the purpose of this document is to explain the rationale of MBTI according to Isabel Myers Briggs who together with her mother Katherine Briggs was the originator of the MBTI. Isabel’s belief was that many problems could be dealt with more successfully if approached in the light of CJ Jung’s theory of psychological types. The implications of the theory go beyond statistics and can be expressed only in human terms.

Personality Differences

Every individual is unique. Each is the product of heredity and environment. we cannot safely assume that other’s minds work on the same principles as our own. Often others do not reason as we do, often others do not value what we do nor are they interested in what interest us. The theory enables us to expect personality differences in particular people and to cope with the people and the difficulties in a constructive way.

Much seemingly chance variation in human behaviour is not due to chance; it is in fact the logical result of a few basic, observable differences in mental functioning, These differences concern the way people prefer to use their minds, the way they perceive and make judgements.

According to Isabel Myers Briggs Perceiving had to be understood to include the process of becoming aware of things: people: occurances and ideas whereas Judgement was to include the process of coming to conclusions about what has been perceived. Together perception and judgement, which make up a large portion of people’s total mental activity, govern much of their behaviour, because perception by definition – determines what people see in a situation and their judgement determines what they decide to do about it. It is reasonable that basic differences in perception and judgement should result in corresponding differences in behaviour.

MBTI was created with the above as a focus for Isabel Myers Briggs and she went on to align these with Extraversion and introversion, which formed the basis of Jung’s work on psychological types.

Extraversion – Introversion

These words are now in common use and Jung called them the Attitudes. MBTI describe Extraversion ‘E’ as energy that seems to flow out and Introversion ‘I’ as energy drawn from the environment and consolidated within one’s position.

Jung combined these two attitudes with the preferences which he labelled rational, and irrational. The rational were Thinking and Feeling and the irrational, Sensing and Intuition, so called because they were ‘mere perceptions which are not evaluated or interpreted.’ By combining these four with either an Extraverted or introverted attitude Jung arrived at his eight types. He was quick to say that since people were unique there was a different type for every single person in the world however to try and gain some understanding of human behaviour he believed that these combinations were categories that most people would fit in varying degrees.

See this article for further information on Jung.


Although the importance of judgement and perception was implicit in Jung’s work it was made explicit by Isabel Myers and Kathering Briggs in the development of the MBTI. With this addition they were able to create sixteen types. Jung had four preferences or functions; Thinking ‘T’ , Feeling ‘F’, Sensing ‘S’, Intuition ‘N’ when he added these to either an extraverted or introverted attitude, four became eight i.e. four extraverted and four introverted types. MBTI took these eight types and added either ‘J’ judging or ‘P’ perception to further divide into the sixteen types used through out the world today

MBTI® Types

The Myers-Briggs Type Indicator┬« (Myers and McCaulley, 1985) is the most widely used measure of Jungian psychological type. The MBTI is a self-report questionnaire that assesses type preferences on Extraversion-Introversion (E-I), Sensation-Intuition (S-N), Thinking-Feeling (T-F), and also on Judgment-Perception (J-P). The J-P scale defines the person’s preferred manner of dealing with the outer world. Judging reflects a closed, organised, decisive approach, whereas Perceiving is more open, flexible and curious. J-P is not specifically recognised as a separate dimension in Jung’s theory, and it is included in the MBTI mainly as a way of indirectly determining which function is dominant.

MBTI types are described using four letters indicating preferences on each scale. This results in sixteen types. These types, and their classical Jungian equivalents, are shown in the table below. In the Jung types, the function in brackets is the auxiliary. Thus IS(T) refers to an Introverted Sensory Thinker with Sensation dominant, whereas IT(S) is the same type, but with Thinking dominant

Each of these attitudes and preferences are measured on bi-polar scales although both Jung and MBTI are keen to point out that behaviour can move along these scales and is not fixed in blood. People can have an extraverted and an introverted attitude to the world. The majority of people who fall close to the middle of this scale can easily switch between these attitudes. There are of course people who will be more clearly defined as, either or, but even they can use both attitudes from time to time.

Using a combination of these scales MBTI create the sixteen types and these are:-

Descriptions of the MBTI types may be found atMBTI Personality Profiles