Predictable and unpredictable sources of variable verb and adverb placement in Scandinavian

Recent research has shown that there is more variation in the placement of verbs and adverbs in Scandinavian than previously thought. This paper argues that the theory of verb movement originally proposed by Bobaljik and Thráinsson [Bobaljik, J.D., Thráinsson, H., 1998. Two heads aren’t always better than one. Syntax 1, 37–71] does in fact predict much of the observed variation, despite recent claims to the contrary. According to this theory, this variation is intimately related to morphological differences between the languages (or dialects): Languages with clearly separable agreement and tense morphology (Icelandic, for instance) have separate agreement and tense projections and this makes verb movement (of the V-to-I type) obligatory because of the nature of checking operations. This does not mean, however, that V-to-I can only occur in languages with rich verbal morphology. The theory also predicts that a certain kind of adverbial modification can trigger V-to-I, but this has typically been overlooked in the literature: If adverbs are specifiers of separate functional projections, then V-to-I is necessary, whereas it is not if adverbs are adjuncts. This means that adverbial adjunction must be the rule in Scandinavian and adverbs in separate functional projections an exception (optionally available for some sentence adverbs but not all in Regional Northern Norwegian, for instance).