Agency (sociology) experiences, and the perceptions held by the society and the individual, of the structures and circumstances of the environment one is in and the position they are born into. Disagreement on the extent of one's agency often causes conflict between parties, e.g. parents and children. The concept of agency has existed since the Enlightenment. René Descartes' phrase Cogito ergo sum stated that anyone who could think is an agent , and any agent capable of knowing that it can think was a subject. Immanuel Kant expanded on this theory by stating that the only way to truly become self-aware is
Cogito, ergo sum As a critic of Cartesian subjectivity, Heidegger sought to ground human subjectivity in death as that certainty which individualizes and authenticates our being. As he wrote in 1927: "This certainty, that "I myself am in that I will die," is the basic certainty of Dasein itself. It is a genuine statement of Dasein, while "cogito sum" is only the semblance of such a statement. If such pointed formulations mean anything at all, then the appropriate statement pertaining to Dasein in its being would have to be "sum moribundus" [I am in dying], "moribundus" not as someone gravely ill or wounded,