Gregory R. Guy & Frans Hinskens Linguistic coherence; systems, repertoires and speech communities. Introduction to Lingua Special Issue on Coherence, covariation and bricolage 1. Terminology In every linguistic system there are some elements, structures and processes which vary, i.e. cases of intra-systemic variation. Each system also contains, clearly, other components that do not vary; as Berruto observes " in language not everything is variable – on the contrary, the system has a large core which is not subject to variation" (Berruto 1987:264, our translation). Similarly, language varieties – dialects, ethnolects, etc. – always share some features with related varieties, while other features are unique to a variety, yielding inter- systemic variation. Both the features which are and those which are not unique for a given variety can be either categorical or (intra-systemically) variable. For the variable ones, the quantitative patterns (say, the probability of occurrence of the dialect variant in the relevant linguistic and extralinguistic conditions) may or may not be unique to that dialect. When specific linguistic systems incorporate multiple variable phenomena – linguistic variables – questions arise as to the ways in which they interact or cohere: Do variants of different linguistic variables tend to co-occur, or do they rather tend to exclude each other, or do they display independent and unrelated patterns of occurrence? To the extent that linguistic variables systematically co-vary, they can be characterized as displaying coherence. In connection with language variation, coherence concerns to what extent multiple co-existing linguistic variables have similar distributions, both internally and in the speech community at large. At the level of the speech community the question is whether (socially) similar speakers have similar patterns of usage of the variables – are the sociolinguistic ‘isoglosses’ more or less coincident, as it were. Coherence thus concerns both the language and the speech community. Le Page & Tabouret-Keller (1985) distinguish communities with focused and communities with diffuse linguistic norms; the latter characterize unstable and highly dynamic sociolinguistic situations, such as in cases of verbal repertoires around a creole language. This distinction seems partly parallel to more versus less coherent linguistic systems. The concept of coherent linguistic systems is problematized by the body of work on language and identity that argues that speakers actively and idiosyncratically select from a palette of variants available in their communities of practice to construct identities, stances, and styles – a process that Eckert (2008) characterizes as ‘bricolage’. The concept of more or less coherent linguistic systems has also been questioned by scholars such as Geeraerts (2010), who doubts that, in a situation with multiple variable phenomena, each and every one with its specific own distribution, there can still be something like a language system. Of course, given that this is in a sense true of every