The main body of this monograph is organized as follows. The first part is about language structure (Chapter 4), the second about language change (Chapter 5), and the third about poetic language (Chapter 6). Qualitatively and quantitatively, the first and second parts are much more important than the third. Its main function is to illustrate the diversity of domains for which relevant hypotheses may be developed. The logic of the argument is quite similar across the individual sections. A review of psycholinguistic evidence serves as the background against which pertinent predictions as to language structure are derived. These predictions are subsequently put to the test and evaluated. This procedure will be adopted irrespective of whether the linguistic data are taken from the relevant literature or presented for the first time. The logic of the argumentation is reflected in the somewhat unconventional structure of the individual sections: psycholinguistic evidence → predictions as to language structure → test and evaluation. My major objective is to assess the value of the processing approach, not the value of more linguistically oriented approaches. This precludes an exhaustive review of the linguistic literature on each topic. Alternative accounts are only considered when they are immediately relevant to the issue at hand, in particular when they can be directly contrasted with the approach advocated here. Unless stated otherwise, the hypotheses advanced below should not be taken automatically to invalidate other claims made in the literature. Rather, they should be construed as additive in two respects. Because of the multiple causation of linguistic phenomena, one explanation does not rule out another, as mentioned. The approach taken here may also provide a deeper understanding of well-known linguistic phenomena by showing how the empirical data follow naturally from a particular conception of language, and how the extant theoretical claims may benefit from being placed in a wider perspective.
The division of this monograph into a synchronic part and a diachronic part is mainly for expository reasons, although this distinction is not clear-cut. Actually, there is some degree of parallelness in the topics that are treated in the diachronic and synchronic sections. The treatment of certain basic issues did not always justify separate synchronic and diachronic sections, as in the case of the first section, to which we now turn.