<p>This book offers an investigation of emotional appeals (pathos) in natural language argumentation. Building on rhetorical theory, psychology, and computational linguistics, it introduces an interactional model of pathos to explain how emotions are elicited and expressed in persuasive discourse. The book traces emotional appeals from classical rhetoric to modern AI-driven methods, showing how emotional language influences perceived argument strength in political, educational, and online contexts. It combines theoretical foundations with empirical studies, including psychological experiments, corpus-based analyses, and large-scale computational modeling using emotion lexicons and large language models (LLMs). By incorporating philosophy, psycholinguistics, and NLP, the book aims to present pathos as a legitimate and measurable element of real-world argumentation.</p>