Camus undertakes to answer what he considers to be the only question of philosophy that matters: Does the realization of the meaninglessness and absurdity of life necessarily require suicide?
He begins by describing the absurd condition: much of our life is built on the hope for tomorrow yet tomorrow brings us closer to death and is the ultimate enemy; people live as if they didn't know about the certainty of death; once stripped of its common romanticisms, the world is a foreign, strange and inhuman place; true knowledge is impossible and rationality and science cannot explain the world: their stories ultimately end in meaningless abstractions, in metaphors. "From the moment absurdity is recognized, it becomes a passion, the most harrowing of all."
It is not the world that is absurd, nor human thought: the absurd arises when the human need to understand meets the unreasonableness of the world, when "my appetite for the absolute and for unity" meets "the impossibility of reducing this world to a rational and reasonable principle."
He then characterizes a number of philosophies that describe and attempt to deal with this feeling of the absurd, by Heidegger, Jaspers, Shestov, Kierkegaard and Husserl. All of these, he claims, commit "philosophical suicide" by reaching conclusions that contradict the original absurd position, either by abandoning reason and turning to God, as in the case of Kierkegaard and Shestov, or by elevating reason and ultimately arriving at ubiquitous Platonian forms and an abstract god, as in the case of Husserl.
For Camus, who set out to take the absurd seriously and follow it to its final conclusions, these "leaps" cannot convince. Taking the absurd seriously means acknowledging the contradiction between the desire of human reason and the unreasonable world. Suicide, then, also must be rejected: without man, the absurd cannot exist. The contradiction must be lived; reason and its limits must be acknowledged, without hope.
While the question of human freedom in the metaphysical sense loses interest to the absurd man, he gains freedom in a very concrete sense: no longer bound by hope for a better future or eternity, without a need to pursue life's purpose or to create meaning, "he enjoys a freedom with regard to common rules".
To embrace the absurd implies embracing all that the unreasonable world has to offer. Without a meaning in life, there is no scale of values. "What counts is not the best living but the most living."
Thus, Camus arrives at three consequences from the full acceptance of the absurd: revolt, freedom, and passion.