Which Are Better - Functions or Dichotomies?

When newcomers to Jungian psychological types take the MBTI - the Myers-Briggs Type Indicator - they are given a "type" that consists of one of the poles of four different dichotomies: (extraversion vs. introversion, sensing vs. intuition, thinking vs. feeling, and judging vs. perceiving). Each of the four letters in the type name reflects a pole of each dichotomy - for example, the type "ISTJ" or "ENFP."

Often the test-taker is also shown his location on a scale of each dichotomy, e.g.
"extraversion 56%, introversion 44%"
The greater the difference between the two poles of the dichotomy, the higher the probability that the dichotomy in question was accurately diagnosed.

The result of this approach is that people get used to thinking that they are "a little bit of both," that they "used to be more sensing than they are now," that they are "sometimes one, sometimes the other," etc.

All of this is foreign to the concept of psychological types introduced by Carl Jung.

Jung spoke not of dichotomies but of functions. He described four functions, each of which comes in an extraverted and an introverted variety. Each person has a dominant function that dominates his or her personality and being. In addition, he postulated the existence of the auxiliary, tertiary, and inferior functions.

Jung did not think of the individual as moving left or right along the scale of a dichotomy during their lives; instead, he talked about the possibility of developing functions' strength, while maintaining that their natural order did not change.

Myers' and Briggs' switch in emphasis from functions to dichotomies made testing more straightforward (more easily quantifiable), but significantly diluted the strength of Jung's original ideas. Dichotomies are easier to measure, but they effectually ignore the main concepts of the typology (which is fine, of course, but it freezes the development of typology theory itself).