The Rational temperament is one of the four temperaments defined by David Keirsey. Correlating with the NT (intuitive–thinking) Myers-Briggs types, the Rational temperament comprises the following role variants (listed with their corresponding Myers-Briggs types): Architect (INTP), Fieldmarshal (ENTJ), Inventor (ENTP), and Mastermind (INTJ).
Rationals are abstract in speech and utilitarian in pursuing their goals. Their greatest strength is strategy. Their most developed intelligence role is that of either the Engineer (Architects and Inventors) or the Coordinator (Masterminds and Fieldmarshals).
As the knowledge-seeking temperament, Rationals trust reason implicitly. They rely on objective observations and factual analysis in any given situation. They seek a logical argument as a basis for action. As strategists, Rationals strive to gain as much information as possible, applying what they learn to develop long-term plans and the steps for achieving them. They are characterized by a tough-minded personal style, tending to pursue either power or understanding. They are often strong-willed, ambitious, intelligent, and self-determined. Subjective thoughts and emotion have no place in the decision-making process of a Rational. Driven to excel, they work hard to achieve their goals, and they do well where they can take control or work independently on a task.
Interests: Rationals are drawn to science and technology. They usually seek careers involving systems—whether mechanical or electrical (as in engineering), organic (as in biology), social (as in psychology or sociology), or organizational (as in business or economics).
Orientation: Rationals are pragmatic about the world around them, having little use for social convention or sentiment except as a means to an end. They weigh logical outcomes before acting, looking for errors in reasoning—in themselves and others. They believe that concepts like good and bad are relative, depending on point of view. They regard time as the duration of events rather than as a continuum. They view place as the intersection of two crossing lines (as in Cartesian coordinates, for example).
Values: Rationals appear calm even in times of turmoil. They achieve this state through an intense concentration of effort rather than through cold-heartedness. They trust reason and strive for achievement. They are knowledge-seekers who aspire to technical wizardry, and so are pleased when others defer to their expertise.
Social roles: In romantic relationships, Rationals want a mindmate with whom they can discuss the topics that interest them, which are usually abstract or theoretical, such as philosophy. As parents, they encourage their children to become self-reliant individuals capable of thinking for themselves. In their professional and social lives, Rationals are visionary leaders, developing and consolidating coherent long-term plans.
When under stress, Rationals may intellectualize or repress their feelings. The informative Rationals (Architects and Inventors) prefer theorizing, designing, and prototyping their ideas, so they can feel overburdened when called upon to finalize their ideas into practical operation by themselves. This can result in feelings of inadequacy, which can lead to poor or no execution.
The directive Rationals (Masterminds and Fieldmarshals) experience stress when their long-range vision is resisted or derailed. They may respond by collecting more and more minute data or by becoming increasingly authoritarian, unaware of how their demands are perceived by others. When confronted with negative consequences in their endeavors, Rationals may experience feelings of incompetence especially if they are not emotionally intelligent. They are frustrated by inefficiency or the perceived illogic of others.
Traits in common with other temperaments 
Keirsey identified the following traits of the Rational temperament:
- Abstract in communicating (like Idealists)
Rationals use concepts, possibilities, theories, and identified patterns as a means for communication. Although Rationals are realistic, the abstract world serves as a tool for thinking independently and developing new ideas that can be used in more practical matters.
- Pragmatic in pursuing their goals (like Artisans)
Rationals are unconventional thinkers when deciding on a task or solving a problem. Individualistic by nature, Rationals observe their own interests as a response to action, free from societal conformity or traditional thinking. Rationals are not necessarily uncooperative, but they will refuse to perform a certain action if it goes against their understanding or experience and is not based on sound logic or the facts (as they understand them) in a given context.
See also 
- Keirsey.com Portrait of the Rational.
- Keirsey, David (1998). Please Understand Me II: Temperament, Character, Intelligence. Del Mar, CA: Prometheus Nemesis Book Company. ISBN 1-885705-02-6.
- Rodionova, D.E. (2007). "Specifics of defensive-coping strategies in connection with typological characteristics of the personality". Psychological Science and Education (in Russian) (Moscow, Russia) (2007, N5): 259–266.
- Berens, Linda V.; Sue A. Cooper (2001). Quick Guide to the 16 Personality Types in Organizations. et al. Huntington Beach, CA: Telos Publications. pp. 15–21. ISBN 0-9712144-1-7.