How do middle voice markers and valency reducing constructions interact? Typological tendencies and diachronic considerations

Middle voice markers are highly polyfunctional items that, among other things, also perform a range of valency-changing operations such as anticausativization and reflexivization. Typological research has shown that individual markers display a great deal of variation with respect to their inventory of functions. Explaining this variation remains a key question that a comprehensive typology of middle markers needs to address. We now know that only a sub-set of the possible polyfunctionality patterns is actually attested and that existing patterns often represent the result of specific grammaticalization processes. In this paper, I explore yet another possible factor, that is, the interaction between middle markers and other valency-changing constructions within the same language. Based on a study of 129 middle-marking languages, I single out two recurrent patterns, that is, complementarity and competition, and argue that their study offers crucial insights in explaining the synchronic polyfunctionality of middle markers.