Simplicity and clarity in the intent of much of environmental design is questioned from a number of points of view. Among other work, recent psychological research shows that humans prefer ambiguous, complex patterns in their visual fields and that this seems a fundamental perceptual preference, applying even to infants and laboratory animals. The overall finding in this area of research is that there is an optimal range of perceptual input preferred generally by subjects with both too simple and chaotically complex visual fields disliked. Building in open–ended, complex, involved, allusive ways is suggested to be more psychologically satisfying than the traditional simplicity and control of the environment sought by many designers. The thinking of a number of designers and writers on urban problems is examined and shown to support this hypothesis.