The concept of strength or weight of an argument appears frequently in argumentation theory. However, there is no commonly accepted definition of argument weighing. Broadly speaking, weighing is understood as either the determination of the degree of support an argument provides for a conclusion, or as the comparison of the relative strength of a set of arguments. This book brings together a representative sample of contemporary treatments of argument strength to facilitate comparison, understanding and discussion. Written by recognized specialists, and containing an introduction establishing the state of the art, it gives coherence to the discussion of the concept of strength of an argument, making it of great interest to anyone interested in language, arguments and logic. The first three parts of this book are devoted to the rhetorical, logical, and dialectical concepts of argument strength and weighing, respectively, while the last two parts are devoted to the weighing of reasons within the deliberative genre and to political and legal argumentation.

Hubert Marraud has been teaching Argumentation Theory at the Autonomous University of Madrid  since 2004, a subject on which he has written five books and more than fifty articles and book chapters.. Many of his publications deal with the concept of argument strength; for example: On the logical ways to counter an argument: A typology and some theoretical consequences (Springer 2019), Holism of Reasons and its Consequences for Argumentation Theory (College Publications 2020), How Philosophers Argue. An Adversarial Collaboration on the Russell-Copleston Debate (Springer 2022, co-authored with Fernando Leal), Argument Dialectics. The place of reasons in logic (2025), and A Case for a Reasons-Based Theory of Argument (Springer 2025). He is currently president of the Sociedad Iberoamericana de Argumentación, director of the Revista Iberoamericana de Argumentación, and a member of the editorial board of the journals Topoi: An International Journal of Philosophy, Hexis. Revista Iberoamericana de Retórica, Eid&A. Revista Eletrônica de Estudos Integrados em Discurso e Argumentação, Quadripartita Ratio. Revista de Retórica y Argumentación, and Éndoxa. Series filosóficas.

Constanza Ihnen Jory holds a Bachelor of Arts degree from the Catholic University of Chile and a PhD in Argumentation Theory, Rhetoric and Philosophy of Language from the University of Amsterdam. She is a Lecturer at the Law Faculty of the University of Chile, where she imparts courses on Argumentation Theory, Philosophy of Language and Legal Reasoning. She is also Director of the Legal Language and Argumentation Program within the same institution. She teaches regularly legal argumentation at the Judicial Academy, the Institute for Judicial Studies and the State Defence Council, in Chile.

Recent publications, relating to the theme of the book, include: “On defeaters and diminishers in John Pollock” (2024, Quadripartita Ratio); “The role of the addressee in evaluating the sufficiency of an argument” (2024, Revista Iberoamericana de Argumentación) and “The concept of sufficiency in defeasible argumentation” (2023, Revista Iberoamericana de Argumentación). She is the co-author of Interpretation, Argumentation and Legal Reasoning (2024, DER Ediciones) and of Education and constitutional debate. Reflections on public deliberation in Chile (2020, Tirant Lo Blanch).

She is currently Executive Director South of the Argumentation Network of the Americas (ANA), one of the editors of the journal Argumentation, and member of the editorial board of Topoi: An International Journal of Philosophy, Revista Iberoamericana de Argumentación and Quadripartita Ratio.