The question of What is a map? inevitably arises within discussions of mapping. Maps have existed as long as language (perhaps longer). They have existed in various forms throughout every group of people and are intelligible to nearly all participants in those groups.Recent academic consensus poses a broad definition of maps as authored, graphic representations of geographical features, concepts, conditions, processes and events.
But maps are not simply 
artifacts that carry meaning with them. They are technologies and assemblages of creating spatialized meaning and filtering that meaning. Mapping is a practice that begins with a and continues through the design, implementation, dissemination, interpretation, and re-imagination of maps by the user. They are texts that re-present spatial complexity and help construct geographic imagination.
Critical Cartography and critical GIS situate our understandings of maps within social and political contexts in which they are produced and made intelligible. Particular attention is payed to how power operates to employ maps to do work within given contexts.
Early in the 20th century, the Institute for Social Research (widely known as the Frankfurt School) investigated the technological and ideological constraints upon people’s creativity and freedom. They developed a critical theory that sought to expose such ideologies and challenge existing power structures. Crampton and Kreiger (2006) describe critique as a “politics of knowledge” that examines the assumptions that shape and enable our knowledge, as well as how these assumptions relate to power and the production of truth (14).
Foucault reconceptualized power as not wholly repressive but offering the grounds or possibilities for knowledge formulation and the production of subjectivity. Foucault accordingly modified the role of critique to one of exploring how knowledge is “established and enabled through historically specific power relations,” not revealing the true nature of reality from beneath ideology (14). To do a critical cartography, then, is not to find fault with a map but to consider what knowledge is presupposed by the map, how it comes to represent that knowledge as truth, and how the map could go beyond those limits and be otherwise.
In the 1980s the scholarship of Brian Harley (1932-1991) posed a fundamental challenge to the discipline of cartography. Drawing from the work of social theorists such as Michel Foucault and Jacques Derrida, Harley shifteds an understanding of maps as scientific, empirical documents to maps as situated within discourses of power-knowledge. “Our task,” Harley wrote, “is to search for the social forces that have structured cartography and to locate the presence of power—and its effects—in all map knowledge” (Harley 1989, 152). The attention to these social forces stood in marked opposition to a more scientifically-influenced view that maps are interpreted in terms of how well they communicate or represent a world detached and external to the map-maker, the map, and its readers. Harley had become skeptical of the accepted value-neutrality of maps and called for an approach that would peal back the layers of ideology encoded into them: Deconstruction urges us to read between the lines of the map—‘in the margins of the text’—and through its tropes to discover the silences and contradictions that challenge the apparent honesty of the image. We begin to learn that cartographic facts are only facts within a specific cultural perspective (Harley 1989, 153).
Re-casting maps as practices involving power relations was “a bold intrusion of poststructuralist theory into cartography’s assumptions of maps as communicative devices” (Crampton 2001, 236). The success of Harley’s initiative is partially explained by the authority of his voice as a long-established empirical cartographer and historian of maps (Edney 2005). Harley’s positionality as a careful and methodical scholar helped give weight to his new-found radicalism that is doubtful other up-and-coming critical cartographers could have achieved.
The tradition of empirical cartography that Harley challenged gained strength in the post-WWII positivist and quantitative shifts within social science generally, and within geography in particular. Famed cartography Author Robinson at the UW-Madison was a principal figure in strengthening the practice of mapmaking as a science adhering to the goals of value-neutrality and an ever-increasing precision of representation. This view of mapping shared with positivism the presumption that science is always progressing. Maps were therefore evaluated in terms of how accurately they depicted the world, and cartography eschewed theorization in favor of improving techniques for more effective communication.
Two implications of this communication model are worth mentioning here. One is a clear separation between cartographer and user, whereby the map was seen simply as an “intermediary between the cartographer and the user” (Crampton 2001, 237). Brian Harley endorsed an “epistemic break” that shifted our understandings of maps as communication systems to investigating them in terms of fields of power relations and exploring the “mapping environments in which knowledge is constructed” (Crampton 2001, 236). This involved examining the social contexts in which maps were both produced and used, a departure from simply seeing maps as artifacts to be understood apart from this context. The second implication is the presumption inherited from positivism that it is possible to separate facts from values. As Harley stated: Maps are never value-free images; except in the narrowest Euclidean sense they are not in themselves either true or false. Both in the selectivity of their content and in their signs and styles of representation maps are a way of conceiving, articulating, and structuring the human world which is biased towards, promoted by, and exerts influence upon particular sets of social relations. By accepting such premises it becomes easier to see how appropriate they are to manipulation by the powerful in society (Harley 2001, 53). Harley was especially sensitive to the use of maps for political propaganda and cultural dominance. Mapping is not just the business of disclosing value-free knowledge about the world, but producing a value-laden knowledge. Harley challenged dominant binary oppositions such as art/science, objective/subjective, and scientific/ideological to “situate map as social documents that need to be understood in their historical contexts” (Crampton and Krygier 2006, 16).
Since Harley’s sudden death in 1991, the field of cartography has burgeoned with theories and writing that recognize maps as social constructions and expressions of power-knowledge (Crampton 2001, Crampton and Kreiger 2006, Wood 1992; Monmonier 1991, 1995; Pickles 2004; Dodge and Kitchen 2000, 2007). These critiques have undermined the idea that maps can achieve an unmediated correspondence with the territory they represent, but instead must employ discourse and rhetoric to work as they do. Monmonier begins his famous book How to Lie with Maps with the declaration that, “Not only is it easy to lie with maps, it’s essential.” (Monmonier 1991, 1). Denis Wood was a leading figure in picking up where Harley had left off, fully engaging with poststructuralism as a way to develop a new critique of maps. Wood writes that, “It is precisely to the extent that the map culturalizes the natural that the cultural production the map is must be naturalized in turn, this to make it easier to accept—as natural—the historically contingent landscape the society that wields the map as brought into being” (Wood 1992, 79). Maps are now seen as potential sites of power-knowledge, operating within more general discourses of power. Maps produce knowledge of geography, people and places. Critical cartography acts to bridge a gulf between a more technically-focused design of maps and a more theoretically informed analysis of power in society. Therefore a critical cartography is informed by critical investigations into space, place, identity, and power. Critical human geography offers much by way of conceptualizing how these fit into an analysis of maps in theoretically problematizing representation and power relations.
