The Role of Functional Factors in Language Change: an Evolutionary Approach

1. Introduction The evolutionary scenario as a model for linguistic change has become more prominent in recent years (Croft 2000, Haspelmath 1999, Kirby 1999). The principled idea behind the evolutionary scenario is quite straightforward: change operates on the basis of variation between available linguistic options and the selection of options in the course of speakers' use, such that particular options may be more and more frequently selected whereas others die out. Its concrete instantiation yet appears to be much more intricate, and raises questions such as: How do new variants come into grammar? What factors guide variant selection? Is language change in any sense 'adaptive'? The aim of the present paper is to test the evolutionary scenario of language change (particularly in its currently most elaborated version due to Croft 2000) against an interesting case of dialect variation, Prepositional Dative Marking in Upper German. It will turn out that the evolutionary scenario is a useful tool for understanding how dialect variation arises. In particular, it provides an explanation for the fact that individual speakers often have the choice between several equally grammatical options. A closer look at this kind of grammar-internal variation reveals that functional properties of the options influence their selection in speakers' use. However, Croft's (2000) model explicitly denies any importance of functional factors for selection. Therefore, I will propose that a reconsideration of the role of functional factors is desirable, and I will show how they can be integrated in our understanding of the selection process. The paper is organized as follows. In Section 2, I will lay out the basic ideas of the evolutionary scenario, based on Croft (2000). The model will be contrasted with an alternative approach due to Haspelmath (1999), which is different in an interesting way, namely in the estimation of the impact of functional factors on variant selection. Section 3 describes the patterns of Prepositional Dative Marking (PDM) found across Upper German dialects. A