The translation of this master work on Karl R. Popper, the founder of a philosophical course which marked the 20th century, not only with a thorough criticism of science, but also with a social philosophy and economic theory, brings a comprehensive study of the biography and work one of the most prominent thinkers whose influence is still felt and fruitful in contemporary times. The book was published with the support of Croatian Ministry of Science, Education and Sports and Austrian Federal Ministry of Science and Education.