Studies in Chinese and Sino-Tibetan Linguistics, 155-165 2014-1-053-009-000241-1 On Coblin’s Law * Guillaume Jacques CNRS-EHESS-CRLAO Coblin’s law is one of the most important phonetic laws in Tibetan historical phonology. This law was devised to explain alternations in the verbal system, but the present article shows that its range of application can be observed in the nominal system too. It also suggests an extension of Coblin’s law: *sNC- > sC-. Key words: Tibetan, phonology, morphology, dissimilation, cluster simplification 1. Introduction In a recent article, Hill (2011:446) has proposed the term “Coblin’s law” for a set of rules of cluster simplification observed in the Tibetan verb, first stated by Coblin (1976). Coblin’s analyses have been widely accepted by specialists of Tibetan historical linguistics, and it seems fitting to provide a contribution on this topic for a Festschrift in honour of Professor Coblin. In this article, I will present the empirical basis of Coblin’s law, show its significance for Tibetan historical phonology outside of the verbal system, and finally propose an extension of this law, namely *sNC- > sC-. 2. Coblin’s three rules Coblin’s law encompasses three distinct phenomena, which we designate respec- tively as rules 1, 2 and 3. Rule 1 concerns the dissimilatory loss of labial stops, which occurs in the past and future stems of b- or p- initial verbs (Coblin 1976:49, 53). An example of the application of this rule is provided by the paradigm of the verb bʲed ‘to do’. We present here the paradigm of this verb with a pre-Tibetan reconstruction based on Coblin’s insight but following Jacques’ (2012a) reconstruction model of pre-Tibetan reconstruction: 1 * In this paper, Tibetan is transcribed using Jacques’ (2012b) transcription system. I wish to thank Nathan Hill, Newell Ann Van Auken and two anonymous review for insightful comments on this paper; I am responsible for any remaining errors. 1 The symbol *V in the pre-Tibetan reconstructions refer to a vowel that was weakened to