In architecture, the doctrine that a building's form should be determined by practical considerations of use, material, and structure and not by a preconceived picture in the designer's mind.
Though not an exclusively modern conception, it is closely associated with the Modernist architecture of the second quarter of the 20th century. The fight for an "honest" form of expression by architects such as Le Corbusier came about as a result of changes in building techniques, needs for new types of buildings, and discontent with historical revivalism, which had been paramount in the 19th and early 20th centuries.