Parliaments are a primary site where political and social democratisation can be seen in action, making parliamentary discourse, as represented in the Hansard of Commonwealth countries, a particularly relevant source of linguistic evidence for the effects of democratisation on language change. South Africa offers an exemplary case of social change which may influence language use. This paper first outlines the historical trajectory of democratisation in the South African parliament. It subsequently sets out to explore patterns of mutual influence between these socio-political changes and changes in the use of English modal auxiliaries of obligation and necessity in a specialised corpus consisting of the South African parliamentary Hansard, sampled at 10-year intervals from 1900 to 2015. The South African data are compared with data from comparable diachronic corpora of the Australian and British Hansard. We interpret our findings in the frame of possible linguistic democratisation aligned with social and political democratisation. Changes in the frequencies of must, should, HAVE to, (HAVE) got to, need and NEED to across the three varieties are reported first, before turning to the semantics of the modals must, should, HAVE to and NEED to. Our findings demonstrate how ongoing language change is receptive to local contexts of use. The data from the South African, Australian and British Hansards show signs of changes similar to the overall changes observed across native varieties of English, such as the gradual decline in the frequency of all modals together, and the increase in frequency of quasi-modals. However, where the British and Australian Hansards match the global trends more closely, the South African data show more signs of deviations from these patterns, which appear to be closely associated with not only demographic changes in parliament, but also the dynamics of conciliation in the broader framework of political democratisation and new patterns of political contestation.

议会是政治和社会民主化在行动中得以体现的主要场所，以英联邦国家议事录为代表的议会话语成为民主化对语言变化影响的特别相关的语言证据来源。南非提供了一个可能影响语言使用的社会变革的典范案例。本文首先概述了南非议会民主化的历史轨迹。随后，该小组着手探讨这些社会政治变化与使用英语模式义务和必要性辅助手段的变化之间的相互影响模式，这些特殊模式包括南非国会议员《国会议事录》，从1900年至10年每十年进行一次抽样2015年。将南非的数据与来自澳大利亚和英国《议事录》的类似历时语料的数据进行了比较。我们在可能的语言民主化与社会和政治民主化相一致的框架下解释我们的发现。频率变化必须，应该，必须，（HAVE）得，需要和必要性，以跨越三个品种公布第一，转向情态动词的语义前必须，应该，必须和NEED到。我们的研究结果表明，持续的语言变化如何适应当地的使用环境。来自南非，澳大利亚和英国议事录的数据显示出变化的迹象，类似于在英语本地变体中观察到的总体变化，例如所有模态的频率一起逐渐下降，以及准模态的频率增加。但是，在英国和澳大利亚议事日程与全球趋势更紧密地匹配的地方，南非的数据显示出更多与这些模式背离的迹象，这似乎不仅与议会中的人口变化密切相关，而且还与该国和解的动态密切相关。更广泛的政治民主化框架和政治对抗的新模式。