  Although information theoretic characterizations of human communication have
become increasingly popular in linguistics, to date they have largely involved
grafting probabilistic constructs onto older ideas about grammar. Similarities
between human and digital communication have been strongly emphasized, and
differences largely ignored. However, some of these differences matter:
communication systems are based on predefined codes shared by every
sender-receiver, whereas the distributions of words in natural languages
guarantee that no speaker-hearer ever has access to an entire linguistic code,
which seemingly undermines the idea that natural languages are probabilistic
systems in any meaningful sense. This paper describes how the distributional
properties of languages meet the various challenges arising from the
differences between information systems and natural languages, along with the
very different view of human communication these properties suggest.
