Equality in language aspects of the theory of linguistic equality

This dissertation is an essay about the assumptions that make the systematic study of language possible. It attempts to refine and make explicit ill-defined ideas which underpin the most fruitful developments in modern linguistics. It charts the evolution of the concept of linguistic equality and its significance in many branches of study; and it tries to elaborate and sophisticate an analysis of the implications of the idea. It attempts to test several hypotheses: that, at some point in the first quarter of the twentieth century, linguistic equality became "an idea whose time had come"; that the idea became a covert hegemonic concept and a necessary if insufficient precondition for all thinking and research about language. There is no pretence that definitive answers have been given; only a hope that interesting and worthwhile questions have been asked.