Certainty in traditional doctrines from the time of Greek philosophy, until Kant and beyond, was based on fixed facts, because they exist in a higher world, and our knowledge of these facts is the ultimate goal, but life in its reality - whether natural or human - is in constant change, so, We must be satisfied with the probability, since certainty is not easy in a changing world, and therefore, we must rely on the facts that exist in the world of change, which are acquired through experience. This book reviews the theories of knowledge of earlier scholars, such as Spinoza, Locke, Newton, Kant, Hill, and Spencer, criticizing them and preaching a new theory of knowledge. John Dewey was born in 1859 AD, in Vermont, where he studied in its schools and university, from which he graduated 20 years later. After 5 years, he obtained his doctorate. While in Chicago, he turned to education and established the laboratory school, which was later known as the Dewey School, and his connection with education has not ceased since then. Because he was studying philosophy at Columbia University, and he was also studying education at the teachers college attached to it. This educational trend made him a philosopher of education.