One of geography's core ideas, scale has become a hotly contested, even chaotic, concept. Until the 1980s, scales (such as the national or regional scales) were frequently employed, but little time was devoted to theorizing scale itself. Scale was a taken-for-granted concept used to impose organization and order on the world. A much vaunted “scale debate” emerged during the 1980s, developed through the 1990s, and erupted in the early 2000s. The debate centers on whether scale is a mental device for categorizing and ordering the world or whether scales exist as material social products.