Heidegger gave this Winter Semester 1928–29 lecture course as Edmund Husserl’s successor at the University of Freiburg. It marks the beginning of the turning on this path of thinking, because Heidegger abandons Husserl’s project of transforming philosophy into a rigorous science. Philosophy is not a science in this sense, since it springs from the ever abundant and ebullient enactment and coming into its own of being-there.
At the beginning of the course, Heidegger divides his introduction to philosophy into three parts: philosophy and science, philosophy and worldview, and philosophy and history. The second part became so extensive that Heidegger could not discuss the third.
In the first part of the course, Heidegger develops the difference between philosophy and science out of the origin of truth. The object of science and its truth are grounded in the essential condition of being-there, that is, transcendence. Transcendence is the disclosing of entities in their being. This disclosure can only happen if being-there lets be entities as they are.
The second part is a discussion of the connection between philosophy and worldview on the basis of the fundamental determinations of being-there: being-in-the-world, transcendence, and understanding of being. Because being-there has been delivered over to the superior power of entities, it is insecure and without a hold. From this insecurity and being without a hold spring two fundamental possibilities of worldview: worldview as security (religion) and worldview as hold (philosophy). Philosophy is an outstanding way of worldview as hold: the letting happen and forming of transcendence as freedom.