Defining the Map: Concepts, Purposes, and the Cartographic Impulse

Defining the Map: Concepts, Purposes, and the Cartographic Impulse

Human beings have been making maps for as long as they have possessed the cognitive capacity to conceive of space and the technical means to represent it. From the prehistoric cave paintings that may encode geographic information to the sophisticated digital globes that populate modern smartphones, the impulse to create spatial representations appears to be a fundamental characteristic of human cognition and culture. Yet this seemingly universal tendency raises profound questions about the nature of maps themselves. What exactly constitutes a map? How do maps differ from other forms of geographic representation? What do all maps share in common, and what accounts for their remarkable diversity? These questions, seemingly simple at first glance, open onto a rich terrain of philosophical, psychological, and historical inquiry that forms the foundation for everything that follows in this book.

The task of defining the map is not merely an academic exercise. Understanding what maps are—and what they are not—provides the essential conceptual vocabulary necessary for engaging meaningfully with the historical material that unfolds across subsequent chapters. When we examine maps from ancient Babylon, medieval Europe, imperial China, or contemporary software applications, we need a framework that can accommodate both the continuities that link these diverse artifacts and the significant differences that distinguish them. This chapter provides that framework, introducing readers to the fundamental concepts, purposes, and characteristics that define cartographic practice across cultures and throughout history.

The Problem of Definition

The question "what is a map?" might seem straightforward, but a moment's reflection reveals its complexity. Consider the variety of objects that might reasonably be called maps: a medieval T-and-O map placing Jerusalem at the center of a circular world, a satellite image of Earth's surface, a subway diagram showing only the network of train lines, a treasure map drawn on parchment, a three-dimensional terrain model, a weather chart displaying atmospheric pressure patterns, and the digital map application on a smartphone. All of these represent geographic space in some way, yet they differ dramatically in their methods, purposes, and relationships to the territory they purport to represent.

Early attempts to define maps focused on their visual and representational qualities. The Oxford English Dictionary, in one of its definitions, describes a map simply as "a drawing of the surface of the earth or a part of it." This definition, while intuitively reasonable, proves inadequate when we consider maps that represent spaces other than Earth's surface, such as lunar maps, star charts, or diagrams of the atom. It also fails to distinguish maps from other types of geographic images, such as paintings of landscapes or photographs of terrain. A watercolor landscape of the English countryside is a "drawing" of the earth's surface, yet we would not ordinarily call it a map.

More sophisticated definitions have emphasized the symbolic and selective nature of cartographic representation. The British cartographer Arthur Robinson and his colleagues, in their foundational text on cartography, defined a map as "a graphic representation of the environment." This formulation introduces the concept of representation rather than simple depiction, acknowledging that maps are not direct transcriptions of reality but rather constructions that involve choices about what to include and how to represent it. The term "graphic" emphasizes the visual nature of maps, while "environment" extends the concept beyond the earth's surface to encompass any space that can be represented spatially.

Perhaps the most influential modern definition comes from the cartographer Mark Monmonier, who describes a map as "a generalized transmission of spatial information." This definition highlights three crucial aspects of maps. First, maps are generalized—they cannot represent every detail of the territory they depict but must select and simplify. Second, maps serve a communicative function—they are designed to transmit information from the mapmaker to the map reader. Third, the information they transmit is spatial in nature—they tell us about the locations, distributions, and relationships of things in space.

Yet even this sophisticated definition raises questions. Does a mental map stored in a traveler's memory constitute a map? Is a map encoded in a database but never visualized on a screen still a map? Is a map that deliberately distorts spatial relationships for aesthetic or political purposes still a map? These edge cases reveal that the boundaries of the category "map" are not entirely sharp—a point that will recur throughout our exploration of cartographic history.

Maps as Selective Symbolic Representations

To move beyond these definitional difficulties, it helps to examine what all maps—regardless of their specific form or cultural context—have in common. Four characteristics stand out as essential to the cartographic enterprise: selectivity, symbolization, generalization, and purpose.

Selectivity refers to the fact that maps cannot include everything. A map of the world cannot show every tree, every rock, every blade of grass. The mapmaker must decide what to include and what to leave out. This decision is never neutral; it reflects the purposes for which the map was made, the audience for which it was intended, and the values and assumptions of the society that produced it. A road map selects roads and ignores vegetation. A political map selects boundaries and ignores topography. A historical map might select the routes of ancient trade networks while ignoring the modern infrastructure that overlays them. Selectivity is not a limitation to be overcome but an essential feature of all maps.

Symbolization is equally fundamental. Maps do not depict reality directly, as a photograph might, but rather represent features through a system of symbols. These symbols may be visual—dots, lines, colors, patterns—but they always involve a translation from the real world to the map. A blue line on a map might represent a river; a red dot might represent a city; green shading might represent forested areas. The relationship between symbol and symbolized is conventional rather than natural; different map traditions have developed different symbol systems. The map reader must learn to read these symbols, just as one must learn to read a written language.

Generalization encompasses the processes by which mapmakers simplify and abstract geographic information. When reducing the complexity of the three-dimensional world to a two-dimensional surface, certain information must be sacrificed. Features may be enlarged beyond their true scale to make them visible and legible. Irregular coastlines may be smoothed. The complex shapes of countries may be simplified. Multiple buildings may be represented as a single block. Generalization is not merely a technical necessity imposed by the constraints of scale; it involves countless judgments about what is important and what can be sacrificed.

Finally, every map serves purposes. Maps are made to be used, and their design reflects the uses for which they are intended. A navigation chart for sailors emphasizes coastlines, water depths, and hazards; a political map for a history textbook emphasizes boundaries and important cities; a topographic map for hikers emphasizes terrain and trails. The purpose of a map shapes every aspect of its design, from the selection of content to the choice of symbols to the level of generalization employed.

These four characteristics—selectivity, symbolization, generalization, and purpose—distinguish maps from other types of images and define the essential nature of cartographic representation. They also help explain why maps vary