Gause’s principle of competitive exclusion is a mainstay of modern ecology. This principle states that, when two species compete for identical resources, one will become locally extinct. Gause’s principle applies directly to blocking and other synonym-based morphological phenomena. If we define the resources of a linguistic sign in distributional terms (following Wittgenstein, Harris, and Chomsky), then Gause’s principle has a wider purview than synonymy, including morphological and phonological conditions on affix distribution, the organization of inflectional classes and genders, and states of competitive equilibrium (e.g., the English comparative). By accepting Gause’s principle as a ‘third factor’ in language organization, we both restrict the scope of purely linguistic principles and explain a much broader range of phenomena than ‘narrow’ frameworks can handle.