In Göttingen, he studied phenomenology with Husserl, and finally wrote his "Habititationsschrift" under the guidance of Max Scheler.

[1] Plessner then held a professorship in Cologne from 1926 to 1933, when he was forced to resign his position because of Jewish ancestry on his father's side.

From Husserl and Scheler, Plessner adapted the idea of the intentionality of consciousness away from the need for a transcendental ego or apperception and instead grounds it in the behaviour (in the broadest sense of the term) of environmentally interactive organisms as a realizing of borders that represents the point where the impulses or growth of organisms meet with their environments, are realized in the act of self-positioning.

These are the scopes of action and understanding that define consciousness and which at the same time ground it in the material world of nature.

For Plessner, our own subjectivity can be understood in terms of the expressive a priori in nature, and our experience of and relationship to it.