Lippmann’s book stands as the first attempt to comprehensively explain how individual psychology, political and social movements, and the mass media both create and unravel shared experiences of reality. The argument he lays out is fairly straightforward: Most of what we think we know about the world has been filtered down to us through external sources, and this information creates a sort of mental map, a collection of simplified representations of the world that help us navigate it more effectively. Inevitably, the accuracy and detail of our maps is directly related to our individual needs and interests—my mental map, for example, contains a great deal of information about Canadian literature, and almost none about how my computer works—but even the things we think we know are mostly just agglomerations of facts we’ve taken on trust from people and institutions relaying them at second- or third-hand. My confidence in saying that reality as I understand it corresponds to the real environment around me is a barometer of my faith in the sources of my information.
The mental maps we carry in our heads determine how we will act in the world, though they will not determine the outcomes of our actions. If I believe that Alaska has white sand beaches, I might book a holiday in Anchorage, but I will probably be disappointed after I arrive. While personal experience can help us correct misconceptions, not everyone can have personal experience of everything that affects their life, so the more abstracted from our personal experience a problem becomes, the more we will need to rely on the guidance and expertise of others. But these guides and experts are also finite individuals who must rely, in turn, on guidance and expertise from other sources, and the information they provide is shaded by their own prejudices and interests, as well as the inevitable distortions and elisions involved in any process of simplification and transmission. “The real environment,” Lippmann writes,
is altogether too big, too complex, and too fleeting for direct acquaintance. We are not equipped to deal with so much subtlety, so much variety, so many permutations and combinations. And although we have to act in that environment, we have to reconstruct it on a simpler model before we can manage with it. To traverse the world men must have maps of the world. Their persistent difficulty is to secure maps on which their own need, or someone else’s need, has not sketched in the coast of Bohemia.