The Diachronic Development of the Serbian Complementizer 'Kako'

Abstract

This paper examines the diachronic development and synchronic distribution of the Serbian form 'kako' (’how’), showing that its interrogative and declarative uses derive from a single inherited composite structure. Drawing on data from Old Serbian texts spanning the twelfth to the eighteenth century, I distinguish two major functions: interrogative 'kako', a manner adverb that participates in regular wh-movement, and declarative 'kako', a complementizer introducing propositional, eventive and irrealis subordinate clauses. I argue that 'kako' originates from a Common Slavic phrasal configuration consisting of a wh-element k- and a manner nominal WAY, whose internal structure became opaque over time. Diachronic evidence shows a gradual increase in the use of 'kako' as a complementizer, accompanied by semantic bleaching, loss of interrogative features, and structural reanalysis in line with syntactic economy principles. A comparison with Romance, particularly the divergent developments of Latin 'quomodo', Friulian 'cemût che' and Salentino 'cu', provides an independent model for understanding how a composite wh-expression can undergo grammaticalization into a C-head. The Serbian data thus offer a well-attested case of a wh-expression grammaticalizing into a multifunctional complementizer, illustrating cross-linguistic pathways between interrogative syntax and complementizer systems.