To appreciate the importance of maps, it will be helpful to compare and contrast maps with language and other types of image. First, consider the way that language and images organize information. Language consists of finite sequences of discrete symbols. Because language presents information in a linear order, it is a good tool if our aim is “to announce goals, discuss sources, explain research strategies, narrate events, [or] summarize arguments” (Monmonier, ix). However, the linearity of language makes it inadequate for representing spatial configurations or a complicated, non-linearly related set of events. Images can handle these cases better since they spread information continuously across a two-dimensional surface. Since images are continuous, we can gain more information by looking at smaller and smaller parts of an image to the extent that the image’s granularity allows. Speaking of maps in particular, Arthur H. Robinson and Barbara Bartz Petchenik write that
This, of course, is the marvel of cartography: the fact that, from a limited number of highly precise and well-chosen measurements and observations, one can produce a map from which can be read off an unlimited number of geographical facts of almost as great a precision. (12-13)
Since language comes in discrete chunks (letters, words, sentences, etc.), there is no possibility of directly extracting more information after we have parsed each component.
Second, consider the way in which language and images achieve representation. Language achieves representation through an arbitrary association between symbols and that which they represent. For example, the English word ‘dog’ could just as well be used to denote cats. Images, on the other hand, achieve representation through a structural similarity which that which they represent. For example, a drawing of Berkey Hall must be such that the lines in the drawing correspond to architectural features of the building, and the lines must be related to each other analogously to the way the corresponding architectural features of the building are related to each other. Thus, when we view an image we perceive some aspect of the structure of that which the image represents. In some sense, a “map is actually a diminutive reproduction of the real space to which it refers” (Robinson and Petchenik, 86).
Next, consider the role of choice when representing with language and various types of image. Language offers its users great freedom in the choice of which concepts to employ when representing. For example, ‘a dog ran across the yard’ and ‘a mammal moved across the yard’ could both represent the same event even though the first sentence uses more specific concepts than the second. Language requires that we break up the world into categories. A way of breaking up the world into categories may obscure certain features of the world or privilege certain interests over others. Certain types of image lack the conceptual freedom of language. An undoctored photograph, for example, leaves little choice to the photographer after it has been decided where the camera should be aimed. Ideally, a photograph presents uninterpreted visual data about a scene as it would appear to a human eye situated there. This point has been disputed by a colleague. I do not wish to argue that a photograph has no ideological content, but I do maintain that representations can be arranged into a spectrum according to how much ideological content is imposed upon them by their authors and that photographs have less ideological content than language.
The freedom of a mapmaker lies somewhere between that of a language user and a photographer. Similar to the language user, the mapmaker can choose which concepts to use in the creation of a map. A map might display population density, temperature, locations of mass shootings, or anything else the mapmaker can dream of. But once the data to be displayed on a map and an appropriate means of displaying it are chosen, the mapmaker is constrained to create the map a particular way. As we will see in the next section, however, the choice of a means of displaying the data can lead to great differences in the map produced.