What are the relationships between philosophy and the history of philosophy, the history of science and the philosophy of science? This selection of essays by Lorenz Krüger (1932-1994) presents exemplary studies on the philosophy of John Locke and Immanuel Kant, on the history of physics and on the scope and limitations of scientific explanation, and a realistic understanding of science and truth. In his treatment of leading currents in 20th century philosophy, Krüger presents new and original arguments for a deeper understanding of the continuity and dynamics of the development of scientific theory. These result in significant consequences for the claim of the sciences that they understand reality in a rational manner. The case studies are complemented by fundamental thoughts on the relationship between philosophy, science, and their common history.