Martin Heidegger was the next big thinker of Phenomenology after Edmund Husserl. The shift from Husserl's phenomenology to Heidegger's can be pin-pointed to the idea the existence itself cannot be described by the phenomenological reduction and epoché.
Heidegger was Husserl's assistant working on his phenomenological method. Husserl's Phenomenology offered Heidegger a method of exploring reality and the demand to return to things themselves. From this, Heidegger realized that it is in the most pragmatic and most naive experience in the world where the human being becomes aware of himself and his environment. Thus the primacy of ordinary everyday life is recognized, where Dasein receives the first concrete experience of the being of that which is.
Heidegger rejected his teacher's concept of Transcendental I or Consciousness. For him life cannot be viewed from outside, but only from within the lived experience of existing. Heidegger rejected Husserl's phenomenological reduction to a transcendental ego that confronted the world merely perceptively. Heidegger describes the phenomenon as “that which shows itself in itself”, as that which shows itself in beings as what they are: the being of beings. From this he concludes: "Ontology is only possible as phenomenology". In other words, the phenomenological inquiry, for Heidegger, must not bear so much on experiences of consciousness, as on the being for whom one can speak of such experiences, and who is thereby capable of phenomenalization, namely Dasein , that is to say, the existing.
In 1933 Husserl and all other Jews were expelled
from the University of
Freiburg while Heidegger was made its rector. The first edition of Heidegger's
1927 "Being and Time" was dedicated to his teacher and initial
patron, but the dedication was removed in his 1941 edition. Heidegger never
apologized for siding with the Nazis, benefiting from their rule and betraying
his biggest teacher.
Read more: Heidegger's "Dasein" compared with Husserl's "transcendental I".