Patten's contribution is one of several in this volume that put cognitive linguistics through its paces in the context of diachrony. She focuses on the history of the it-cleft in English.
Jt-clefts have not received very much attention in the historical literature apart from handbooks such as Visser (1963). Recently, however, they have started to attract more attention, especially perhaps within the generative tradition, see e.g. Ball (1991, 1994) and Perez-Guerra (1999). Patten's study starts by outlining the generative account of Ball, who suggests that it-clefts emerged in Middle English from the NP BEON Rel-Clause pattern. Ball's story bears considerable similarity to Lightfoot's classical account of the rise of English modal verbs in terms of the proposed abrupt profile of the change. Patten contrasts this with a more gradualist reconstruction, where the it-cleft is seen as a development from the Old English hit-cleft construction. As a result, some properties of the Present-day English cleft, related to their peculiar syntax as well as their specificational function, fall into place.
From the point of view of the volume, a particularly interesting shortcoming Patten reveals in generative work is that the pattern on which Ball suggests the it-cleft is based is actually very rare, occurring only in translations from Latin. In the Generative model frequency is generally not given very much importance, but most cognitive linguists subscribe to the usage-based model, in which frequency plays a crucial role in relation to grammatical representation (see e.g. Bybee 1985, Croft 2000). It is intuitively implausible that such a rare and restricted pattern should have given rise to the relatively frequent it-clefts, and the usage-based model provides a natural and empirically based framework for this position. Another respect in which Patten's contribution engages with the questions posed in this volume is that she argues that Ball disregards the Old English hit-clefts because they do not fit the abrupt, Lightfootian model of change.
The contribution by Trousdale is historical as well. Like Patten, the author compares a generative linguistic account (Felser & Britain 2007) to a cognitive, construction-based one. Yet where Patten's chapter deals with the fairly common it-clefts, Trousdale studies the rather infrequent what with construction, e.g. What with the high cost of living in this area, double income households are the norm.
Trousdale starts by summarizing Felser & Britain's (2007) analysis, which rejects a constructionist view of the pattern, arguing instead that the meaning of what with is fully compositional and can be accounted for within the Minimalist model of phrase structure. As Trousdale notes, semantic unpredictability was indeed a property of constructions according to Goldberg (1995). This view has been abandoned by Goldberg (2006), however, on the condition that the construction is frequent enough to become entrenched with its fully predictable meaning. The unpredictability stipulation was, moreover, never part of the construction-based cognitive approaches of Langacker (1987) and Croft (2001).
Trousdale moves on to discuss what with from the perspective of construction grammar, drawing attention to the various sub-types of the construction. Their gradual historical development is seen to consist of a number of micro-changes (Brinton & Traugott 2005: 150). Some of these changes involve narrowing and reduction, while others display broadening and expansion. We observe reduction in terms of the prepositions that co-occur with (the ancestor of) this construction, with e.g. what by and what from falling out of use. On the other hand, while the construction used to be mainly restricted to two coordinated noun phrase complements, other types of complements have become possible over time, with no need for coordination. Overall, the profile of the change fits especially well with the recent literature on "grammatical constructionalisation" (e.g. Himmelmann 2004, Traugott 2010). However, in relation to the theme of the volume Trousdale also notes that recent generative literature pays more attention to micro-changes (see e.g. Roberts 2010). He concludes that there is thus (an opportunity for) a degree of rapprochement between the generative and cognitive approaches to language change.