[that we have worked out] is first and foremost the presupposition for the fact that perhaps, in large measure, existence [228] may be worry and hardship in that pre-scientific sense.

As long as existence is, it is always in a specific mode. But that means that existence is not set, once and for all, in just one specific mode that would exclude any ability to be otherwise. Properly this means that whenever existence behaves in a particular way, that way remains only one possible way of behaving. Existence can, in principle, give up that first way and enter upon a different way of behaving. Therefore, “possibility” is a determination that belongs in principle to the modes of comportment, and this possibility does not disappear when a particular comportment is de facto chosen and lived out.

In this more detailed interpretation of comportments we also encounter difficulties insofar as the concept of possibility has up until now gone entirely unclarified in scientific philosophy. And to the degree that it has been clarified, the explanations typically only go as far as possibility in the modal sense, where it is seen in the context of statements and of the certitude that can accrue to them. In that case, the idea of possibility is seen in connection with actuality and necessity as determinations of being, i.e., the being of nature in the broadest sense. The meaning of possibility and the kind of structures of possibility that pertain to existence as such have been entirely closed off to us until the present. Therefore the explication of existence constantly runs up against difficulties because it refuses from the start to conduct investigations into the issue by making any use of traditional concepts.

One of the basic possibilities of existence’s being that we have already mentioned is that of authenticity and inauthenticity. I will go into this briefly because we will be making use of this distinction later in clarifying the difference between authentic and inauthentic truth. In looking at the phenomenon of care, we have brought out three [229] structures of existence: being-in-the-world, being-with-others, and being-concerned-about-oneself. Furthermore, as so characterized, this existence is essentially always my existence. In ontological statements about this being that I call existence, the personal pronoun must necessarily be also mentioned: this being [Seiendes] that has the character of existence is an “I am” or a “you are.” The way we understand this is that existence, by its very essence, is always mine, and not in the sense of some formal generality. Rather, existence is always mine to be in this way or that and to be such and so. Existence is always mine insofar as existence has a priori decided the way in which it is mine—not that existence itself has necessarily made the decision, but rather in the sense that “a decision has already been made” about my existence. “Existence is always mine” means factically that existence has a self that must be appropriated in one way or in another and to one extent or another. It has a self