Indo-European Linguistics
Bloomfield's earliest work was in historical Germanic studies, beginning with his dissertation, and continuing with a number of papers on Indo-European and Germanic phonology and morphology. His post-doctoral studies in Germany further strengthened his expertise in the Neogrammarian tradition, which still dominated Indo-European historical studies. Bloomfield throughout his career, but particularly during his early career, emphasized the Neogrammarian principle of regular sound change as a foundational concept in historical linguistics.
Bloomfield's work in Indo-European beyond his dissertation was limited to an article on palatal consonants in Sanskrit and one article on the Sanskrit grammatical tradition associated with Pāṇini, in addition to a number of book reviews. Bloomfield made extensive use of Indo-European materials to explain historical and comparative principles in both of his textbooks, An introduction to language (1914), and his seminal Language (1933). In his textbooks he selected Indo-European examples that supported the key Neogrammarian hypothesis of the regularity of sound change, and emphasized a sequence of steps essential to success in comparative work: (a) appropriate data in the form of texts which must be studied intensively and analysed; (b) application of the comparative method; (c) reconstruction of proto-forms. He further emphasized the importance of dialect studies where appropriate, and noted the significance of sociological factors such as prestige, and the impact of meaning. In addition to regular linguistic change, Bloomfield also allowed for borrowing and analogy.
It is argued that Bloomfield's Indo-European work had two broad implications: "He stated clearly the theoretical bases for Indo-European linguistics..."; and "...he established the study of Indo-European languages firmly within general linguistics...."
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