Types of rationals
Architects need not be thought of as only interested in drawing blueprints for buildings or roads or bridges. They are the master designers of all kinds of theoretical systems, including school curricula, corporate strategies, and new technologies. For Architects, the world exists primarily to be analyzed, understood, explained - and re-designed. External reality in itself is unimportant, little more than raw material to be organized into structural models.
Fieldmarshals will usually rise to positions of responsibility and enjoy being executives. They are tireless in their devotion to their jobs and can easily block out other areas of life for the sake of their work. Superb administrators in any field - medicine, law, business, education, government, the military - Fieldmarshals organize their units into smooth-functioning systems, planning in advance, keeping both short-term and long-range objectives well in mind.
Inventors begin building gadgets and mechanisms as young children, and never really stop, though as adults they will turn their inventiveness to many kinds of organizations, social as well as mechanical. There aren't many Inventors, say about two percent of the population, but they have great impact on our everyday lives. With their innovative, entrepreneurial spirit, Inventors are always on the lookout for a better way, always eyeing new projects, new enterprises, new processes.
Masterminds are head and shoulders above all the rest in contingency planning. Complex operations involve many steps or stages, one following another in a necessary progression, and Masterminds are naturally able to grasp how each one leads to the next, and to prepare alternatives for difficulties that are likely to arise any step of the way. Trying to anticipate every contingency, Masterminds never set off on their current project without a Plan A firmly in mind, but they are always prepared to switch to Plan B or C or D if need be.