Abstract Presidential speeches are often investigated as privileged readings of the state of the nation. A recurrent theme in the speeches of Nigerian presidents is corruption, and this reflects the enormity of national concern with the impact corruption has on social life, the economy and infrastructure development. Whereas research on corruption appears to be overwhelming due to its significance, questions useful for a more nuanced understanding of the subject have rarely been posed. Thus, little is known about the intensity of articulation of corruption over time, how social moments of enunciation can shape the articulation of corruption, as well as the types of corruption that are of concern. To provide answers to these questions, this article uses corpora, combined with transitivity analysis in systemic functional linguistics and critical discourse analysis, to analyse corruption in Nigeria from novel and especially diachronic standpoints. Findings show that (1) the articulation of corruption in the speeches, including the types expressed, have varied over time, and (2) the moments of enunciation of the speeches are often shaped, among others, by a need to gain legitimacy on assumption of office, a perception of how corrupt a preceding administration was and a verbalised determination to tackle corruption.

中文翻译：

---

尼日利亚总统演讲的历时性腐败

摘要总统演说经常被当作对国家状况的特权读物进行研究。尼日利亚总统演讲中经常出现的主题是腐败，这反映了国家对腐败对社会生活，经济和基础设施发展的影响的极大关注。尽管由于其重要性，对腐败的研究似乎不胜枚举，但很少提出有益于对问题更细微理解的有用问题。因此，人们对腐败的表达强度随着时间的流逝知之甚少，社交场合的话语表达如何影响腐败的表达，以及人们所关注的腐败类型，人们所知甚少。为了提供这些问题的答案，本文使用语料库，结合系统功能语言学中的及物性分析和批判性话语分析，从新颖性和历时性的角度分析尼日利亚的腐败现象。研究发现表明：（1）演讲中的腐败行为，包括表达的类型，随着时间的流逝而变化；（2）演讲中表达腐败的时刻通常是由于需要获得假设的合法性而形成的。的职位，对上届政府腐败的理解以及对付腐败的口头决定。