The actuation problem

IntroductionThe term actuation problem was first introduced and defined by Weinreich, Labov and Herzog (1968:102). In their words: (1) The actuation problemWhat factors can account for the actuation of changes? Why do changes in a structural feature take place in a particular language at a particular time, but not in other languages with the same feature, or in the same language at other times? This actuation problem is one of five related problems that Weinreich, Labov and Herzog (1968) pose to historical linguists, in an attempt to break down the hows and whys of language change into manageable chunks. It is difficult to overstate the importance that Weinreich, Labov and Herzog accord to the actuation problem: they refer to it as ‘the very heart of the matter’ (1968: 102). Elaborating on their initial formulation, later in the paper they state: … even when the course of a language change has been fully described and its ability explained, the question always remains as to why the change was not actuated sooner, or why it was not simultaneously activated wherever identical functional conditions prevailed. The unsolved actuation riddle is the price paid by any facile and individualistic explanation of language change. It creates the opposite problem – of explaining why language fails to change. (1968: 112) This chapter will provide an overview of the problem in the domain of historical syntax, as well as evaluating a number of potential solutions. In order to know whether a particular theory or explanatory principle succeeds in solving the ‘riddle’ of actuation, it is necessary to contrast the actuation problem with the other four key problems that Weinreich, Labov and Herzog outline for a theory of linguistic change; §19.2 serves this purpose, and also relates the actuation problem to questions of prediction and explanation. §§19.3 and 19.4 each survey a family of related proposals in the literature, dealing with ‘internal’ and ‘external’ factors respectively. §19.5 concludes.