In lecture four, we explore the historical transition from natural philosophy to modern science during the 19th and 20th centuries, examining how the professionalization of science led to the view that all truths are scientific truths. We trace key developments including Darwin's Origin of Species, the Industrial Revolution's technological successes, and the coining of the term "scientist" in 1837. The lecture concludes by examining the Vienna Circle's logical positivism and its eventual failure, highlighting the philosophical tensions that arise when science attempts to explain all aspects of human experience, including consciousness, morality, and meaning.