Credible intermediaries: rhetorical strategies for an ethos of interactional expertise

Intermediaries such as think tanks, commissions, and non-profits produce large volumes of grey literature to inform public policy. Yet, the rhetorical practices that make their grey literature reports credible and persuasive remain poorly understood. Because intermediaries operate between multiple communities, they must build credibility without necessarily possessing expertise in each domain - a distinctive challenge with practical implications for their evidence-to-policy communication.

To (1) investigate rhetorical strategies intermediaries use to establish credibility as grey literature authors; and (2) explore how rhetorical ethos adds explanatory power to help understand intermediaries' communication with policy audiences.

Using a qualitative multiple case study design, I analyzed three influential reports on antimicrobial resistance written by non-governmental intermediaries. Each case combined close reading of report texts with analysis of production and reception materials and 23 semi-structured interviews with authors, contributors, and policy audience members.

Intermediaries cultivated a distinctive ethos of interactional expertise through two key rhetorical strategies. First, they performed an extended invention process, publicly showcasing how they learned over time and engaged diverse stakeholders. Second, they emphasized inclusivity, transparency, and independence as signature virtues.

Foregrounding ethos clarifies how intermediaries can navigate their rhetorical situation and write more persuasively to inform policy. The study contributes both theoretical insight and practical guidance: intermediaries can enhance credibility by publicly showing their process of engagement and by enacting virtues that leverage their unique position between communities.