This book constitutes the refereed proceedings of the 6th International Conference on Logic and Argumentation, CLAR 2025, held in Taiyuan, China, during June 14-16, 2025. The 22 full papers included in this book were carefully reviewed and selected from 38 submissions. These papers focus on the recent advancements in the field of logic and argumentation, as well as their applications in various areas of Artificial intelligence (AI), such as explainable AI, ethical dilemmas, reasoning about uncertainty and knowledge representation.