Giannini’s model differs importantly from Myers’ in that it does not restrict us to just one predominant function pair associated with one’s preferred perceiving and judging processes. His model provides a greater degree of flexibility in the developmental expression of type-related behaviors as well as enhanced adaptive power for engaging and responding to our various environments.
function pairs
Jung’s approach is based on pairs of polarities. Getting eight functions with such a ‘binary approach’ requires three levels of dichotomy. Jung clearly explained his split of the rational functions into two opposite functions and the same for the irrational functions; but he never provided a theoretical context for a third “dimension” of psychological type.