Heidegger’s rethinking of notions of being pivots on a critical reformulation of the concepts of possibility and in particular its relation to actuality, through the prism of temporality and finitude. Already in Being and Time, Heidegger indicates that being understood as the temporal and historical occurrence of what is should be thought primarily in terms of possibility rather than actuality. In Basic Concepts, he in fact indicates that the actual is primarily the possible, since it appropriately outlines the span of actuality, which, always already open onto the future, transpires in terms of the possible: “Not the oft-mentioned ‘actual’ is the actual, but the possible.
For Heidegger, human existence means a continuous projection ahead of itself as an existence whose understanding of itself is never finished or complete.
