Diachronic change from Washington to Obama: the challenges and constraints of corpus-assisted meaning analysis

Building on previous findings investigating diachronic change in specialized domains, in particular State of the Union addresses over a long-term time span (Bayley and Bevitori 2015), this chapter aims at exploring what can and, conversely, cannot, be achieved by combining Corpus Linguistics procedures with the analysis of texts and discourse within the theoretical concerns of Systemic Functional Linguistics. Moving beyond textual ‘aboutness’, it is argued that certain kinds of lexicogrammatical information can be detected through the analysis of a non-annotated corpus; moreover, with particular reference to the case-study, it will also be claimed that the rhetorical thrust of State of the Union addresses has gradually, but consistently, shifted from a more ‘informative’ style, i.e. presenting a report, to a more ‘persuasive’ one, i.e. soliciting action, over time.