Contents: Preface. Part I: Gaining a Sensible and Useful Conceptual Framework. Beliefs, Knowledge, Arguments, and Decisions. The Representational Status of Statements: True or False. Domains of Representation. Apparent Representation Only: Pragmatic Priorities. Combinations of Statements in Arguments. Formal Calculi in Beliefs and Arguments: Errors. Classifying Errors and Weaknesses in Arguments. Part II: Who Are the Victims of Mistaken Beliefs and Weak and Invalid Arguments and Why? Beliefs and Arguments in Action. Human Sources of Errors in Beliefs and Inadequacies in Argumentation. Gaining Competence in the Critical Evaluation of Beliefs and Arguments. La Condition Humaine in 21st-Century Quasi-Democracies. Postscript.