There are a couple more contradictions between the terminology and theories of Carl Jung and Isabel Briggs Myers than the J/P difference I discussed in yesterday's blog.

Two or Three Categories?

Carl Jung's typology contains eight types and Isabel Briggs Myers' typology contains 16 types.  This in itself is not a contradiction, because the sixteen Myers Briggs types are arrived at simply by dividing each of Carl Jung's types into two.

There is, however, a contradiction because in reality, beneath the 'headline' of 8 types, Jung saw more categories and allowed for a 'middle group' between the opposites.  This contradiction can be seen in Isabel Briggs Myers and Jung's different treatment of Extraversion and Introversion, where in Myers Briggs Theory there are two categories and in Jung's theory there are three:

"There is, finally, a third group... the most numerous and includes the less differentiated normal man... He constitutes the extensive middle group... I call the first group extraverted and the second group introverted" (p516, Psychological Types)

Is Type Inborn or Developed?

Isabel Briggs Myers wrote:

"Type theory assumes that children are born with a pre-disposition to prefer some functions over others" (p14, 1985 Myers Briggs Type Indicator Manual)

I am grateful to Lenore Thomson Bentz (author of Personality Type: An Owner's Manual) for pointing that Jung never said that there is an inborn pre-disposition for particular functions.  From the parts of Jung's writings I have looked at on this topic (primarily Psychological Types and CG Jung Speaking) he does discuss inborn predispositions, but his discussion of what is inborn is limited to:

- a predisposition towards Extraversion/Introversion

- particular talents/abilities

- archetypes

An individual's talents/abilities may tend to favour some functions over others, but different talents may also favour opposing functions.   However, Jung didn't say we are born a type, but that we become a type when something becomes differentiated and 'habitual'.  For example:

"From a great number of existing or possible attitudes I have singled out four... Thinking, Feeling, Sensation, Intuition.  When any of these attitudes is habitual... I speak of a psychological type." (p482, Psychological Types, Jung's emphasis)

Conclusion

Whilst there are differences between Jung and Briggs Myers on these points, they are relatively minor for most applications of type theory.  Isabel Briggs Myers made her model simple enough so that we could comprehend the somewhat complex and inaccessible theory of Carl Jung (leaving aside topics such as archetypes, the collective unconscious, complex theory, etc.).  Her hope was that everyday conflicts and problems might be dealt with more successfully, and that is what her model achieves.