The Stranger is a novel that follows a man named Meursault, a Frenchman living in Algeria, through his daily routine. The story begins with Meursault confronting the recent death of his mother. He says, "My mother died today, or maybe it was yesterday," revealing his detachment from details, emotions, and possibly relationships. He moves through life, enjoying its daily and novel pleasures, without reflecting much on himself, his circumstances, or even his decision-making process. He lives in a seaside town in Algeria, has a job and an apartment and early in the book, begins an affair.
Despite Meursault's lack of attachment or daily routine, he is a fully formed character. He enjoys his meals, lives independently, and begins a romance. At this point in the story, neither existentialism, nor Freudian psychology, nor Marxism, nor feminism have entered the picture, but when he begins his affair that changes.
Feminism is represented in The Stranger through the character of Marie. Although she is his lover, Meursault is detached from her emotionally. She satisfied his physical needs, but he is passive. He does not view her as a person, but a vehicle to serve his sexual needs, which aren't far removed from his need for food and drink. This portrait serves as a foil to feminism, but it could be argued that Meursault's underlying misanthropy reveals a dislike of not only women, but humankind.
Marxism, the doctrine that workers are exploited by a system that ensures workers will be alienated from their own labor, slips into this story. Both Meursault and Marie have jobs, but neither is given particular status. Class is never mentioned in the story, and class divisions seem trivial — all humans are thrown into one big pile of sensuality, detachment, and fate. In this way, The Stranger is a denial of Marxism — which becomes subsumed to existentialism, as the story develops naturally without the doctrine even emerging as important.
Freudian psychoanalysis posits that individuals have repressed feelings that lead to irrational actions, often based in unresolved parental conflicts from childhood. The opening scene in The Stranger sets the stage for Meursault to be anti-analytical; he never wonders about himself, nor his relationship to his mother. He does not question why he does things, simply doing them and, for the most part, enjoying them — yet being alienated from his enjoyment due to his feelings of alienation. But, he is pulled along by fate, as we discover by the end of the story. His actions may be connected to unconscious fears, as when he shoots a man for no apparent reason, a man he can barely see. Meursault embodies Freud's belief that pleasure and self-preservation are the two priorities for all men and also demonstrates how we are often motivated by forces larger than ourselves.
The most important concept in this novel is existentialism, the fact that our existence is bizarre and unknowable, yet we soldier along as if our lives have meaning. Meursault has an existential crisis in the last quarter of the book when he is unjustly accused of a crime, imprisoned, and suddenly aware he will die. He has no control over his fate yet as he stares into the night sky and comprehends "the benign indifference of the stars" he suddenly realizes he did enjoy his life, and it did have meaning, and feels a bit attached to it. The absurdity, of course, is that it's too late.