Skepticism is one of the most prominent philosophical movements. Its emergence coincided with the emergence of philosophy as a movement opposed to all certainty and to every established, established truth, which is the primary task of philosophical thought. Indeed, it can be said that skepticism was an enlightened school opposed to any intellectual hegemony. This became evident with the Renaissance, which relied heavily on skepticism, or what is called "neo-Pyrrhonism." The rediscovery of Empiricus's texts had a significant impact on the intellectual and philosophical transformations that extended into the modern era. Within a historical narrative context, this book addresses skepticism in three different eras, not only to trace the development of this powerfully influential school from the Greek era through the Middle Ages and the Age of Enlightenment to the present day, but also, above all, to present the true meaning of skepticism and its importance in ending the movement of stagnation and obscurantism. Despite the accusations leveled against skeptics, and the condemnation of them all as people of false argumentation and the restriction of the term (sophist) to those who deny (absolute truths), skepticism is not the bluster of one person who must be silenced, nor is it merely a series of doubts related to religious beliefs. Rather, it is a philosophy that encompasses all areas of life. Doubt is necessary for the movement of thought and a condition for development. Progress would not have occurred without those philosophers who confronted dogmatism and the dominance of a single truth. Therefore, doubt must always be present to correct and expose false positions. It is the path to demolishing everything that is fixed, certain, final and absolute.