How did phenomenology influence existentialism?

Phenomenology, founded by Edmund Husserl, provided the methodological foundation for existentialism by offering a rigorous way to describe conscious experience without relying on prior scientific or philosophical assumptions. Existentialist thinkers adapted this approach to explore the structures of human existence and the nature of Being.12

Key influences include:

• Methodological Framework: Existentialists adopted the phenomenological method—such as the "dismantling" of traditional metaphysics—to uncover the "primordial truth" of human experience.1
• Martin Heidegger: As a student of Husserl, Heidegger transformed phenomenology into an ontology. He used it to analyze Dasein (human being) as a set of worldly involvements, shifting the focus from pure consciousness to the individual's historical and practical situation.21
• Jean-Paul Sartre: Sartre utilized Husserl’s concept of intentionality to analyze consciousness and freedom. He integrated these phenomenological insights into his own existential psychoanalysis, defining humans as beings of possibility.23
• Maurice Merleau-Ponty: He applied phenomenology to the human body, arguing that perception is the mediating link between human existence and the world.3