The following is adapted from Linda V. Berens and Dario Nardi, The 16 Personality Types: Descriptions for Self-Discovery (Telos Publications, 1999) *Used with permission.
Over the years, philosophers and behavioral scientists have been trying to find ways to understand what they call personality. Personality has many meanings. We like the definition given by Salvatore Maddi:
Personality is a stable set of characteristics and tendencies that determine those commonalities and differences in the psychological behavior (thoughts, feeling, and actions) of people that have continuity in time and that may not be easily understood as the sole result of the social and biological pressures of the moment.*
Personality typing is popular. Most widely used models ultimately describe sixteen discrete patterns. This booklet provides descriptions that represent the best of all these models. These sixteen type descriptions are not derived from a single framework such as social styles, temperament theory, or psychological type. They are descriptive of sixteen universal themes that exist in and of themselves, yet reflect all of the above frameworks.
Historically, professionals have alternated between the idea that personality is inborn and the seemingly opposite view that it results from our experiences. The most current thinking is that personality is both inborn and conditioned by the environment.
The Contextual Self
The contextual self is who we are in any given environment. It is how we behave depending on what the situation requires. The idea of a personality "type" doesn't leave out freedom of action in the moment.
The Developed Self
When the contextual self becomes habitual and ongoing, it becomes a part of the developed self. Personality development is influenced by our choices and decisions (free will) as well as by interactions and roles (social field theory).
The Core Self
An aspect of our personality exists from the beginning of our lives. This aspect of ourselves is in our genes, our DNA. We are born with a tendency to behave in certain ways, which influences how we adapt, grow and develop.
When looking at personality types, all three of these aspects must be considered. Current behavior and adaptations may or may not be consistent with the true self. All are interrelated.
*Salvatore R. Maddi, Personality Theories: A Comparative Analysis, 3d ed. (Homewood, Ill.: The Dorsey Press, 1976), p. 9.