Matthiessen 28th Pacific Asia Conference on Language, Information and Computation pages 5-26 do; and language is modelled as a probabilistic system (long before the advent of today's "probabilistic linguistics", as formulated in Bod, Hay & Jannedy, 2003, and used within "statistical natural language processing", Manning & Schütze, 1999).
variation can be -and has been -characterized in probabilistic terms within the overall theory of language as a probabilistic system (e.g.