I searched for a thread that examined this aspect of the MBTI personality theory. Typeism provides a unique opportunity to look into some aspects of prejudicial thinking because there are people who are sincere in their assumptions regarding type. With the other "isms" like sexism, racism, etc. there is a cultural and historical context that influences the assumptions of prejudice. These can often be connected to underlying political and religious thought. Most people learn these assumptions from their parents and authorities they trust. My own understanding was that prejudice was primarily driven by this deep context and indoctrination during childhood. This is not typically the case with typeism. This is a fresh way of categorizing people and yet shares a similar outcome without culturally based prejudices. It is interesting just how powerful these prejudicial conclusions can become even without any deeper cultural context. Or is there a deeper context that is labeled differently and this system is a way of expressing those unquestioned values?
What are the reasons that even intelligent, insightful people embrace assumptions about others and label them as inferior based on their MBTI category when it is in itself a system that is not scientifically founded? As a system that does not have a valid method of measurement, it would seem the critical thinker would have some reservations about its validity.
This is a link to a review that summarizes the book, "The Cult of Personality..." by Dr. Cathy Goodwin.