What if the greatest intellectual weapon ever forged was not a theory, not a proof, but a refusal to believe? In the eighteenth century, a cheerful Scotsman named David Hume dismantled the foundations of human knowledge with nothing more than a sharp eye and an uncomfortable question: How do you actually know what you think you know? Two and a half centuries later, his challenge has not been answered. It has only grown more urgent. The Skeptic’s Armor takes readers on a journey through Hume’s radical skepticism and its astonishing resonance with modern science. From quantum mechanics and neuroscience to artificial intelligence and virtual reality, the book reveals how Hume’s insights about causality, perception, morality, and the limits of reason find confirmation—and complication—in the discoveries of our own time. But this is not a museum tour of a dead philosopher’s ideas. It is a practical guide to thinking clearly in a world saturated with unexamined claims, false certainties, and seductive illusions. The book proposes a concept of functional skepticism—an approach that balances doubt with action, caution with courage, and intellectual humility with the willingness to live and decide in a universe where nothing is absolutely certain. Written with wit, clarity, and a deep respect for the reader’s intelligence, The Skeptic’s Armor is for anyone who has ever suspected that the world is not quite what it seems—and wants to know what to do about it.