In C.J. Cherryh’s classic novel Wave Without A Shore, the scholarly inhabitants of planet Freedom believe that they can decide what is real. They choose not to see or acknowledge the indigenous aliens or a human underclass, both of whom share their city. This theme occurs elsewhere in science fiction – in Ulan Dhor, one of Jack Vance’s Dying Earth tales, the Grey and Green tribes share a ruined city but are magically unable to see each other; also in China Mieville’s recent novel The City and The City, two cities share the same space but citizens are discouraged, on pain of disappearance by sinister secret police, from seeing each other.
A related idea was put forward by avant garde architects Superstudio in the 70s. In the City of the Book, the last of their satirical Twelve Cities, they imagined a city made up of tunnels in which two contradictory moral codes co-existed. A book of laws could be read by sunlight on the city’s exterior or by filtered light in the tunnel cavity - in each location different words would appear, so the same citizens would behave in an upstanding moral manner in one setting but indulge in excessive vice in the other. The authors claimed that this, like their other City concepts, was based on a real city although they did not reveal which one they had in mind.
Wave Without A Shore is about post-modernism. Modernism is the idea that reality is empirical – it can be measured and understood; it’s closely related to science and to the Enlightenment. Post-modernism isn’t one philosophy and there are post-modernist trends in every walk of life, but the cross-hatch is that most of these ideas downplay or refute the existence of any base reality, instead emphasising a reality that is constructed by ourselves.
On this topic I’ve always taken the Philip K. Dick line as a good working definition: reality is that which does not go away when you stop believing in it. A version of this argument existed long before post-modernism ever reared it’s socially constructed head – Plato challenges Socrates to refute the suggestion that he only exists in Plato’s imagination. Socrates, kicking a stone, replies “I refute it thus.” From the title onwards, Cherryh’s novel is very much a response to post-modernist ideas and is about the hubris of choosing what is real.