existential
in
Into the Wild

relating to or dealing with existence -- especially with human existence

relating to existentialism; a philosophical movement that assumes each person is free to determine what is important in their existence -- rather than that being determined by convention, God, and/or authority figures

Existentialist belief is varied. All such beliefs stress the need for each individual to find their own way, but most stress that there is no rational way of finding it.

Atheistic existentialists often stress isolation of the individual in a hostile or indifferent universe. Some stress life without meaning. Others stress loss of a shared morality, uninhibited exercise of power, and/or hedonism.

Existentialism is often associated with philosophers and writers such as Kierkegaard, Nietzsche, Heidegger, Jaspers, Marcel, Sartre, Camus, Dostoevsky and Kafka.

meaning too rare to warrant focus:

Much more rarely, in logic, an "existential quantifier" denotes the existence of a member in a set to which something is applicable. It is contrasted to a universal quantifier which applies to all members of a set. For example: "What is the scope of the existential quantifier?"