In architecture, Rationalism (Italian: razionalismo) is an architectural current which mostly developed from Italy in the 1920s and 1930s. Vitruvius had claimed in his work De architectura that architecture is a science that can be comprehended rationally. The formulation was taken up and further developed in the architectural treatises of the Renaissance. Eighteenth-century progressive art theory opposed the Baroque use of illusionism with the classic beauty of truth and reason.
Twentieth-century Rationalism derived less from a special, unified theoretical work than from a common belief that the most varied problems posed by the real world could be resolved by reason. In that respect, it represented a reaction to Historicism and a contrast to Art Nouveau and Expressionism.
The term Rationalism is commonly used to refer to the wider International Style.[1][2][3][4]