Explaining the irreversibility of grammaticalization

The paper deals with the unidirectionality of grammaticalization, which is explained by Haspelmath within a usage-based theory of language change as proposed by Keller, who sees language change as an invisible-hand process. Haspelmath focuses on the maxim of extravagance as the main factor for irreversibility. The notion of extravagance was criticised by Geurts as being inappropriate and unnecessary for explaining the unidirectionality of grammaticalization. Haspelmath's explanation is extended by Huelva Unternbäumen, who derives the irreversibility of grammaticalization from three conditions that have to be fulfilled grammaticalization and degrammaticalization to take place.