In a chaotic era of information overload, cultivating strong judgment skills is crucial for maintaining clarity of mind. This concise and practical book elucidates the fundamental concepts and principles of rational thinking, using relatable real-life examples. With warm-up exercises, chapter-end summaries, and practical exercises, readers can easily acquire essential rational thinking skills. This serves as both a foundation for further knowledge pursuit and a tool to safeguard against deception and manipulation in everyday life.