Existence is subjective only because what one person experiences is always different from another's experience. It is always particular and individual—always my existence, your existence, her existence. Humans are therefore called, in Martin Heidegger's phrase, Dasein *, “there being” because they are defined by the fact that they exist or are in the world and inhabit it. Existence requires the focus on investigating the meaning of “Being.”

Many problems arise because people believe that their subjective experience of the world is objectively actual for everyone.

Existentialism is a philosophical theory that people are free agents who have control over their choices and actions.

Existentialists believe that society should not restrict an individual's life or actions and that these restrictions inhibit free will and the development of that person's potential.

*Being and Time by Martin Heidegger

Because he asks these questions he therefore exists as a being.