The most widely used assessment of normal personality traits is the Myers-Briggs Type Indicator (MBTI). In this chapter, I compare the RMP with the MBTI. I put forth the following four hypotheses relevant to both scientific and professional interests.

1. Hypothesis 1. The MBTI is a valid measure of a narrow range of human motivation and is not a measure of “preferred ways of perception and judgment” as commonly claimed (Myers et al., 1998).

2. Hypothesis 2. The MBTI's four personality dimensions are too few in number to provide a comprehensive explanation of personality type.

3. Hypothesis 3. The RMP of sixteen basic desires can validly assess all of the personality traits assessed by the MBTI without paying any attention to MBTI type theory or to Jung's theory. In contrast, the MBTI cannot validly explain all of the personality traits assessed by the RMP.

4. Hypothesis 4. In leadership training and human development workshops, the joint use of the MBTI and the RMP stimulates the self-discovery process more fully than when only one instrument is used.

Historical background

Galen (a.d. 129–a.d. 200) held that combinations of four humors — black bile (melancholic), yellow bile (sanguine), blood (choleric), and phlegm (phlegmatic) — determine our personalities. Galen hypothesized that individuals produce different amounts of each humor — your personality, for example, depends on the relative amounts of each humor specific to your body. Galen's theory of humors dominated personality typing from about a.d. 200 until the nineteenth century.