  The Fundamental Theorem of Language Change (Yang, 2000) implies the
impossibility of stable variation in the Variational Learning framework, but
only in the special case where two, and not more, grammatical variants compete.
Introducing the notion of an advantage matrix, I generalize Variational
Learning to situations where the learner receives input generated by more than
two grammars, and show that diachronically stable variation is an intrinsic
feature of several types of such multiple-grammar systems. This invites
experimentalists to take the possibility of stable variation seriously and
identifies one possible place where to look for it: situations of complex
language contact.
