Correlated Grammaticalization: The Rise of Articles in Indo-European
One of the central empirical goals of historical linguistics is to distinguish probable from improbable changes. This includes not only singleton developments, but also interactions among multiple changes. That is, does one linguistic change become more (or less) likely given the occurrence of some other change? Investigations of this question have been hampered by methodological issues, not the least of which is how exactly correlations between changes should be measured. In this talk, I take up the question of the relationship between the grammaticalization of definite and indefinite articles in Indo-European. Did the emergence of one type of article facilite (or inhibit) the rise of the other? Using methods developed for the study of correlated evolution in biology (Pagel 1994, 2006), I argue that indefinite articles became more likely to emerge in the wake of the grammaticalization of definite articles. The history of articles in Indo-European is thus an example of correlated grammaticalization. More generally, my results provide further evidence for the view that grammaticalization is not simply a matter of universal principles and pathways, but is also crucially conditioned by pre-existing linguistic structure.