Absurdism refers to the philosophical theory that human existence is meaningless and senseless. The desire to evoke meaning from a purposeless existence through religion or philosophy means that humans live out their absurdities by adhering to ideologies that fail to recognize this absurdity. Sartre embraces absurdism and condemns those who live their lives in service to authority or to concepts of external power.

Throughout Being and Nothingness, Sartre uses the term “appearances.” In philosophy, this refers to what seems to be or what can be perceived. In Sartre’s work, appearances are aligned with phenomenon: They refer to experiences and what is revealed through the senses. Sartre claims that appearances create essences.

Traditionally, the idea of authenticity means being oneself and living in a way that aligns with one’s desires and beliefs. Sartre’s definition differs slightly. Since he sees the world as absurd, he prescribes that living authentically is the only way to break the pattern of its absurdity. This means that humans should construct their own definitions of morality and make choices independent of external forces. In doing so, they live authentically.