premise: The answer has nothing to do with their cause , however , but with the simple fact that dictionaries are not exercises in bi - unique substitutability ; in other words , if one of the senses of run is ` operate ' ( as in She runs an engine factory ) , that does not make it valid to assume that one can substitute operate for run in We run in the marathon every year . Although recognizing this as a shortcoming of dictionaries and assigning it arbitrarily to what , for lack of
hypothesis: Dictionaries are shorter exercises in bi - unique substitutability .