This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Martin Heidegger studied under Edmund Husserl and was appointed in 1928 to the chair at Freiburg that Husserl had previously held. The year before, in his own founding book, Being and Time (1927), he had dedicated it to Husserl in friendship and admiration. Their relationship was in fact complicated and occasionally strained even at its most cordial. He also, in that same book, redirected phenomenology so thoroughly that some historians treat it as a second founding rather than a continuation. Husserl's phenomenology started from consciousness, the transcendental ego bracketing the world to examine how objects are given to it. Heidegger thought this starting point already smuggled in centuries of philosophical assumption, that a human being is fundamentally a knowing subject standing apart from a world of objects it observes. His own starting point was Dasein, being-there, his term for the distinctively human way of existing, which he insisted is never first a detached observer but always already thrown into a world of practical concern, using tools, inhabiting relationships, absorbed in projects before it ever stops to contemplate anything. The illustrative case is a fountain pen: when writing is going well, Heidegger argued, a person does not perceive the pen as an object with properties at all, it affords writing, and in affording writing it sends the writer to the paper, the paper to the desk, the desk to the chair, disappearing into the activity itself, and it is only when the pen runs dry or is missing that it surfaces as a thing to be looked at and reasoned about. Ordinary theoretical knowing, on this account, is not the basic relationship between a person and the world, it is a breakdown mode, parasitic on a more fundamental, practical absorption Husserl's method had passed over. Heidegger called his own project fundamental ontology, the question of what it means for anything to be at all, approached through the one being that already has some understanding of being built into its own way of existing. The break cost the two men their relationship in the years that followed, but the philosophical break was real independent of the personal one: it reoriented phenomenology from a theory of consciousness toward a theory of existence, and that reorientation is what made Sartre's and later existentialist phenomenology possible at all.