This chapter lays out the theoretical devices on which the subsequent analysis builds. The first section introduces the phonological architecture used in the book, and in particular the distinction between the phonological, phonetic-phonological, and phonetic levels of representation, which underpin the notion of the life cycle that is central to the book’s argument. The second section recaps current views on the mechanisms of language contact and the role that phonological patterns can play under different contact scenarios. This is followed by a discussion of areal effects in phonology generally and some case studies beyond northern Europe, which exemplify various possibilities for recovering the history of contact from attested phonological patterns. The third section discusses the mechanisms of phonological convergence and the possible uses of sound patterns in diagnosing language contact in the past. Finally, the fourth section lays out the theory of the life cycle of phonological processes and introduces key related notions such as rule scattering and rule generalization, and lays out a proposal for how the life cycle can be used in examining language contact in the past.

This chapter offers a general discussion of the phonetics and phonology of stop preaspiration, a central empirical concern of the book, in both synchronic and diachronic perspective. Preaspiration has a reputation as a cross-linguistically unusual feature, and I argue that this exoticization has hindered a more critical approach. Building on recent empirical work that has contributed to demystifying this phenomenon, the chapter lays the groundwork for the analysis of preaspiration in subsequent chapters. It presents the general approach to the phonetics and phonology of laryngeal contrast employed in the book; justifies the definition of preaspiration and analytical criteria used in subsequent analyses; and provides an explicit account of how preaspiration is expected to develop diachronically within the context of the life cycle. The chapter also offers critical discussion of the link between preaspiration and consonant quantity, a recurrent theme in the literature that is relevant to all the case studies considered later in the book. It concludes with a brief account of phenomena allied to preaspiration such as sonorant devoicing, and their import for the book’s argument.