One of the biggest differences between Isabel Briggs Myers and her mother Katherine Briggs with my father, David Keirsey, is how one does analysis of an individual's personality. Isabel and Katherine essentially adopted Carl Jung's incomplete analysis, with some key changes and observations of Isabel that spanned all the kinds of personality. My father recognized Isabel Myers observations of different kinds of people mirrored and expanded on his own observations. He immediately accepted Myers very brief descriptions of the sixteen types of characters, but quickly realized that her atomistic (reductionistic) approach to describing personality had a problem. The first problem was she had no sense of Temperament. The second problem was her descriptions were composed by elements, that did not consider the individual as a whole, but as a sum of parts. The third problem Myers described what she guessed was in people's minds, which is not directly observable.
One can visualize the two differing characterizations as illustrated by the following two diagrams.


So looking at an individual, using Myers Scales [I/E, N/S, T/F, J/P], one can get confused by looking for specific behavior, for example, that is "P." The problem is that one is looking at a "part" of the person, which does not consider the WHOLE person. The behavior of a "
P" of a ENT
P can be quite different from the "
P" of an INF
P. The same can be said of the others: E, I, N, S, T, F, and J.
In our analysis of human action, we try to establish the Temperament first, then the agenda Roles: Enterprising vs Inquiring, then the four Roles: Initiating versus Contending, coWorking versus Responding. We try to consider the WHOLE PERSON as we study their actions.