Introduction: Many health professions education (HPE) scholars frame assessment validity as a form of argumentation in which interpretations and uses of assessment scores must be supported by evidence. However, what are purported to be validity arguments are often merely clusters of evidence without a guiding framework to evaluate, prioritise, or debate their merits. Argumentation theory is a field of study dedicated to understanding the production, analysis, and evaluation of arguments (spoken or written). The aim of this study is to describe argumentation theory, articulating the unique insights it can offer to HPE assessment, and presenting how different argumentation orientations can help reconceptualize the nature of validity in generative ways. Methods: The authors followed a five-step critical review process consisting of iterative cycles of focusing, searching, appraising, sampling, and analysing the argumentation theory literature. The authors generated and synthesised a corpus of manuscripts on argumentation orientations deemed to be most applicable to HPE. Results: We selected two argumentation orientations that we considered particularly constructive for informing HPE assessment validity: New rhetoric and informal logic. In new rhetoric, the goal of argumentation is to persuade, with a focus on an audience's values and standards. Informal logic centres on identifying, structuring, and evaluating arguments in real-world settings, with a variety of normative standards used to evaluate argument validity. Discussion: Both new rhetoric and informal logic provide philosophical, theoretical, or practical groundings that can advance HPE validity argumentation. New rhetoric's foregrounding of audience aligns with HPE's social imperative to be accountable to specific stakeholders such as the public and learners. Informal logic provides tools for identifying and structuring validity arguments for analysis and evaluation.