Plessner's philosophical anthropology is presented as a non-naturalistic philosophy of nature. Such a position is attractive and indispensable, for instance, to all debates concerning personhood and human dignity. Plessner's work rests on a conception of philosophy that distinguishes without exception the contents of possible experiences from their conditions of possibility. Thus, Plessner's anthropology is a theory of categorial contents, but not in the aprioric sense according to which they would be assumed to be (logically, not only temporally) prior to all experience. Plessner avoids such a misconception by structuring his philosophy in a reflexive way. Therefore his basic philosophical category or idea—eccentric positionality—doesn't mean a property of human or any natural beings, but the categorial frame called personhood which is in use when we identify empirical properties of humans. The challenge in understanding personhood as conceptually independent of empirical properties consists in distinguishing between the contingency of personhood and arbitrariness.