Scholars in pragmatics have long been interested in how knowledge is construed, contested and legitimised. Much recent work in pragmatics has focused on developing more detailed theoretical understandings of epistemic positioning and epistemic authority, including in institutional contexts which are typically characterised by knowledge asymmetries and power inequalities. Yet the relational consequences of epistemic positioning have received little attention, therefore, this article aimed to investigate how authority and community are simultaneously negotiated in interaction, turn by turn. Taking a social semiotic approach, combining analysis using exchange structure, evidence and epistemic stance frameworks, this article examines a public hearing of the 2010 Senate Committee Inquiry into Donor Conception in Australia. Findings reveal four cumulative discursive patterns: donor-conceived witnesses positioned their lived experience as non-negotiable, cast doubt on fertility practitioners' expertise, layered opinions upon experience and employed recognised knowledges to bolster authority. This article introduces the concept of ‘lived expertise’; that is, authority grounded in experience and sustained through awareness of additional forms of experiential and institutional knowledges. Empirically, this study sheds light on how donor-conceived people – as people with lived experience – expand the subject positions afforded to them in institutional contexts, inviting legitimacy and belonging.

语用学学者长期以来一直对如何解释、争论和合法化知识感兴趣。最近的许多语用学工作都集中在对认知定位和认知权威进行更详细的理论理解，包括在通常以知识不对称和权力不平等为特征的制度背景下。然而认知定位的关系后果却很少受到关注，因此，本文旨在探讨权威和社群如何在互动中同时轮流协商。本文采用社会符号学方法，结合使用交换结构、证据和认知立场框架的分析，研究了 2010 年澳大利亚参议院委员会对捐赠者概念调查的公开听证会。调查结果揭示了四种累积的话语模式：捐赠者受孕的证人将他们的生活经历视为不可协商的，对生育从业者的专业知识表示怀疑，根据经验分层发表意见，并利用公认的知识来增强权威。本文介绍了“生活专业知识”的概念；也就是说，权威植根于经验，并通过对其他形式的经验和机构知识的认识来维持。从经验上看，这项研究揭示了捐赠者受孕的人——作为有生活经验的人——如何扩大机构环境中为他们提供的主体地位，从而获得合法性和归属感。