This study presents a view of diachronic change in language, according to which one of the fundamental factors motivating syntactic change is to be found in the conflicting interaction of principles determining the language organization. Specifically, it will be argued that principles of structural nature and principles of perceptual nature are in conflict in languages of the SOV type, because of the relative clause construction. The way in which a relative clause is structured in an SOV language is an obstacle to its effective perceptual processing. It will be argued that this conflict is one of the major factors determining the diachronic change of a language from an OV to a VO typology.