I will start the paper with a brief theory of metaphor, one that goes beyond mere rhetorical formulations and links language with the creation of perceived realities. Following it will be a survey of what I consider to be the six most pervasive metaphors of human communication in everyday life. Each turns out to entail its own logic for human interaction and the use of each creates its own social reality. This descriptive account is intended to provide the 'data' or the ground from which I shall then develop several radical constructivist propositions. These are intended to reflect on how a social reality could be conceived that does afford so many incompatible ways of communicating, on the individual contributions to understanding, understanding of understanding, and viability in practicing such metaphors, on what makes communication a social phenomenon, on three positions knowers can assume in their known and the theories of communication commensurate with these positions. Then I will sketch some aspects of mass communication in these terms and comment on its research. Propositions of this kind should prove useful in efforts to construct scientific communication theories or, to be less ambitious, to understand communication as a social phenomenon that involves each of us with other human beings. For lack of space, the concern for issues of mass communication had to be severely curtailed, leaving the readers to continue on their own. (Klaus Krippendorff)