Martin Heidegger (1889-1976) was a German philosopher whose Being and Time (1927) is one of the most influential and most difficult books of the twentieth century. He wanted to reopen the oldest question in philosophy: what does it mean for anything to be? He began with the being for whom that question matters, ourselves. He called the human being Dasein, an ordinary German word for existence that literally means “being-there.”
Being-in-the-world
Descartes had pictured the self as a thinking mind looking out at a separate world and wondering whether it was real. Heidegger thought this got things backwards. We are not detached spectators. We are always already being-in-the-world: absorbed in practical activity, surrounded by tools, tasks and other people. A carpenter does not first see a hammer as a lump of matter with properties; she grasps it as something for hammering, within a web of purposes. Only when the hammer breaks does it stand out as a mere object to be stared at. Our basic relation to the world is practical involvement, not theory.
Thrownness and care
We find ourselves thrown into a world we did not choose. Heidegger's term thrownness names this: finding ourselves in a time, place, language, body and family we never picked. Yet we are also always projecting ourselves toward possibilities, pressing ahead into what we might become. Heidegger called the basic structure of human existence care: we are beings for whom our own existence is always an issue.
The “they” and inauthenticity
Most of the time we live as das Man, usually translated as “the they” or “the one.” We do what one does, think what one thinks, enjoy what they enjoy. This is not a moral failing; it is ordinary everyday life. But it is inauthentic in Heidegger's technical sense, because we let the anonymous crowd make our choices for us instead of owning them. The German words for authentic and inauthentic are built on eigen, meaning “own.”
Being-toward-death
What can pull us out of the they? Heidegger's answer is death. Everyone knows that “one dies,” but the they treats death as something that happens to others, someday. Death is in fact my ownmost possibility, because no one can die my death for me. It is certain, while its time is uncertain. To exist as being-toward-death is to face one's own mortality and let it clarify what matters. Anxiety, which makes the familiar world suddenly strange, can open this awareness. The result is meant to be not gloom but resoluteness: taking up one's life as one's own.
Heidegger and the label
Sartre drew heavily on Being and Time. But Heidegger rejected the existentialist label, most clearly in his Letter on Humanism (1947), where he distanced his thinking about being from Sartre's focus on human freedom and choice.
Heidegger and Nazism
Heidegger's personal history is deeply troubling, and it must be stated plainly. He joined the Nazi Party in 1933, the year he became rector of the University of Freiburg, and gave speeches supporting the new regime. He resigned the rectorship in 1934 but remained a party member until 1945, and after the war he never offered a clear public apology. Postwar denazification authorities barred him from teaching until 1951. His private notebooks, published from 2014 as the Black Notebooks, contain antisemitic passages. Scholars still debate how far his politics connect to his philosophy. Many think his insights can be studied critically without excusing his choices; others argue the two cannot be cleanly separated. Either way, his case is a reminder that brilliance in thought is no guarantee of wisdom in life.
Worked example: when the routine breaks
Daniel is an accountant in his forties. His days run smoothly: the same train, the same coffee, the same jokes with colleagues, the same shows in the evening. He has opinions about the news that match what everyone around him thinks. In Heidegger's terms he lives as the they. Nothing is wrong with this, exactly; it is how most of life goes.
Then a close friend dies suddenly at forty-five. At the funeral, people say what one says: “He's in a better place,” “At least it was quick.” Daniel notices how these phrases hold death at arm's length, as if it happens to other people.
Over the following weeks Daniel feels anxious, though nothing in particular threatens him. His familiar routine suddenly looks strange, like Heidegger's hammer that stands out only when it breaks. He realizes that his own death is certain, its time unknown, and that no one can live or die it for him.
Being-toward-death does not lead him to despair. Instead it clarifies things. He asks which of his habits he actually chooses and which he simply drifts along with. He keeps his job, which he now sees he values, but he stops putting off visiting his aging father and starts the painting classes he always said he would take “someday.”
This is resoluteness in Heidegger's sense: not a dramatic break with ordinary life, but taking it up as one's own. Daniel's thrownness (his family, his city, his temperament) remains. What changes is how he owns it.