"Real science does not deal with things, but with concepts that stand for things." Wilhelm of Ockham. Whether Charles S. Peirce's assertion that "the entire modern philosophy is based on Ockhamism" is accurate remains to be seen. The fact is that the significance of Wilhelm of Ockham for understanding the intellectual genealogy of modernity and the present, which would remain incomprehensible without considering the philosophical achievements of the Middle Ages, has only received due attention in recent decades. This applies to his groundbreaking contributions to logic and epistemology as well as to his challenges in the fields of philosophy of science, metaphysics, and theology, and especially to his political philosophy. One can only do justice to the approach and goals of this thinker by considering his work as a whole.