Not mentioned here (though hopefully it is in Emre’s book) is the fact that the test grew out of Carl Jung’s careful work with individual subjects, using what he developed as a sophisticated word association test, to establish the existence of objective, psychological differences of perception and cognition between people to foster empathy and understanding. (See his 575 page volume, “Studies in Word-Association: experiments in the diagnosis of psychopathological conditions carried out at the psychiatric clinic of the university of Zurich” published in 1915.) What Jung termed Psychological Typology can be very helpful in family counseling, therapy, bridging personality differences between individuals. It has been developed further into a means of understanding human variety (similar to but different from the Enneagram), and you can read about its subtleties and usefulness in studies by John Beebe, MD and other Jungian psychoanalysts. But just as Sigmund Freud’s nephew, Bernays, took his uncle’s work to create the tricks of advertising in the US, so Jung’s usefully descriptive, typological subtleties have been made popular, shallow, and simplistic in the Meyers-Briggs test and its spin-offs. It has thus been grabbed and debased by our current economic system to sort through the “types” of personalities most effective to support capitalism. To focus only on the misuse is like blaming the discovery of iron ore for the creation of bullets — ignoring history and the introverted Feeling and Sensate Functions.