ISTJ (Introversion, Sensing, Thinking, Judging) is an acronym used in the Myers-Briggs Type Indicator (MBTI) publications to refer to one of the sixteen personality types. The MBTI assessment was developed from the work of prominent psychiatrist Carl G. Jung in his book Psychological Types, which proposed a psychological typology based on his theories of cognitive functions.
From Jung's work, others developed psychological typologies. Well-known personality tests are the MBTI assessment, developed by Isabel Briggs Myers and Katharine Cook Briggs, and the Keirsey Temperament Sorter, developed by David Keirsey. Keirsey referred to ISTJs as Inspectors, one of the four types belonging to the temperament he called the Guardians.
ISTJs are faithful, logical, organized, sensible, and earnest traditionalists. They earn success by thoroughness and dependability. Shutting out distractions, they take a practical, logical approach to their endeavors. Realistic and responsible, they work steadily toward their goals. They enjoy creating order in both their professional and personal lives.
Centered on their inside world, ISTJs are persons of thoughts and (sometimes) emotions. They prefer dealing with the present and factual, using various options to make decisions. They are also keen observers of life, well prepared for most eventualities, and have a good understanding of most situations. They believe in practical objectives and they value traditions and loyalty.
In both their professional and personal lives, individuals of this type are rather quiet and serious. ISTJs are extraordinarily persevering and dependable. The thought of dishonoring a contract would appall a person of this type. When they give their word, they give their honor. ISTJs can be counted on to conserve the resources of the institution they serve and bring to their work a practical point of view. They perform their duties without flourish or fanfare; therefore, the dedication they bring to their work can go unnoticed and unappreciated.
While not directly seeking leadership positions, ISTJs are often placed in such roles. They build a reputation for reliable, stable, and consistent performance that causes others to select them to lead. ISTJs use their past experience and their factual knowledge in their decision making.
For the ISTJ, love means commitment, steadiness, and consistency. ISTJs expect themselves and their mates to be responsible, practical, and dependable. When in a relationship, they behave appropriately for what the situation or their role demands. For example, if the relationship is in the courting stage, the ISTJ will exhibit courting behaviors, such as giving boxes of candy, red roses and presents.
They like learning activities that allow them time to reflect and think. Material that seems too easy or too enjoyable leads ISTJs to be skeptical of its merit. Because of their practical outlook, ISTJs clearly delineate between work and play. Therefore, their ideal learning environment is task-oriented, has a clear schedule, and has a clear and precise assignment.
ISTJs often work for long periods, devoting their energy to tasks that they see as important to fulfilling a goal. However, they resist putting energy into things that don't make sense to them, or for which they can't see a practical application. They prefer to work alone but can work well in teams when the situation demands it. They like to be accountable for their actions, and they enjoy positions of responsibility. They have little use for theory or abstract thinking, unless the practical application is clear.
In general, ISTJs are capable, logical, reasonable, and effective individuals with a deeply driven desire to promote security and peaceful living. They can be highly effective at achieving their goals—whatever those may be.
According to the "Guidelines for Ethical Use for Certified MBTI Professionals, "only the individual can verify his or her own best-fitting type." The MBTI instrument focuses on cognitive processes, which are not observable, and therefore speculation regarding another person's type is not an appropriate use of the instrument. The Keirsey Temperament Sorter, however, focuses on behavior, which is observable. For illustrative purposes, Keirsey and others, as referenced below, have identified well-known individuals whose behavior is consistent with a specific type. Unless otherwise noted, the categorization of the individuals below, whether living or dead, as ISTJs is a matter of expert opinion rather than the result of actual personality testing of the named individual.