Phenomenology has at least three main meanings in philosophical history: one in the writings of G.W.F. Hegel, another in the writings of Edmund Husserl in 1920, and a third, deriving from Husserl's work, in the writings of his former research assistant Martin Heidegger in 1927:
The difference in approach between Husserl and Heidegger influenced the development of existential phenomenology and existentialism in France, as is seen in the work of Jean-Paul Sartre and Simone de Beauvoir. Munich phenomenology (Johannes Daubert, Adolf Reinach, Alexander Pfänder in Germany and Alfred Schütz in Austria), and Paul Ricoeur have all been influenced. Readings of Husserl and Heidegger have also been crucial aspects of the philosophies of Jacques Derrida and Bernard Stiegler.