This Summer Semester 1928 lecture course, given under the title Logic, was the last Heidegger taught at the University of Marburg. During this course, he delivered a memorial for Max Scheler on 21 May 1928. The course pursues the metaphysical foundations of logic in light of the question of being. It belongs to the transitional phase in Heidegger’s thought from the existential analysis of being-there in Being and Time to the task of overcoming metaphysics in his later thought.
In the introduction, Heidegger describes traditional logic as the science of determining thinking, which expresses itself in assertions, and contrasts it to what he calls philosophical logic. Plato and Aristotle transformed the latter into the former. Heidegger’s course thus becomes an attempt to develop a philosophical logic through a destruction of traditional logic.
In the first main part, Dismantling Leibniz’s Doctrine of Judgment Down to Basic Metaphysical Problems, Heidegger attempts to uncover the metaphysical foundations of logic through an interpretation of Gottfried Wilhelm Leibniz’s metaphysics with regard to the function metaphysics has as the ground for his logic. He focuses his attention on Leibniz’s definition of substance as force and of the latter as representation. Leibniz thus anticipated both Friedrich Nietzsche’s philosophy of the will to power (force) and the modern philosophy of worldviews, which regards the world as a representation of the subject.
The second main part, The Metaphysics of the Principle of Reason as the Foundational Problem of Logic, is both a confrontation with the philosophy of Scheler and an introduction to Being and Time. Heidegger converts fundamental ontology into metontology, in which the latter “overturns” the former. Metontology has for its proper theme the being of entities in a whole (das Seiende im Ganzen) and is also the domain of the metaphysics of existence. It is only possible on the basis and in the perspective of the radical ontological problematic. The problematic demands an interpretation of beingthere on the basis of temporality and, from this interpretation, an elucidation of the intrinsic possibility of our understanding of being. Fundamental ontology is the whole of founding and developing ontology. The existential analysis of being-there, and the analysis of the temporality of being, turn at the same time into metontology. In their unity, fundamental ontology and metontology constitute the complete concept of metaphysics.
The introduction to the problem of time leads to an extensive discussion of transcendence and intentionality. They are both attempts to think the basis of the subject–object–relation. In their last long conversation, Heidegger and Scheler agreed on four points: (1) The problem of the subject–object–relation needs to be raised completely afresh; (2) it is not a question of epistemology; (3) the problem has central import for the possibility of metaphysics; and (4) the moment is here to develop metaphysics from the ground up.
Heidegger would later develop the detailed investigations of the concept of world in conjunction with the problem of ground into his treatise On the Essence of Ground.