Hayden Carruth’s introduction to Sartre’s Nausea:
Existentialism is a recoil from rationalism. Not that Existentialists deny the role of reason; they merely insist that its limits be acknowledged. Most of them probably like to think that their speculations are eminently reasonable, yet not rational; and they emphasize the distinction between the terms. In particular, Existentialism is opposed to the entire rationalist tradition deriving from the Renaissance and culminating, a hundred-odd years ago, in the “cosmic rationalism” of Hegel.
Hegel submerged the individual consciousness in a grand unity of ideal mind. But for the Existentialist, who insists that reality is only what he himself knows and experiences, this is meaningless. Not only that, it is cruel and coercive. The Existentialist knows that the self is not submerged, it is present, here and now, a suffering existent, and any system of thought that overrides this suffering is tyrannical. “A crowd is untruth,” Kierkegaard repeats with choric insistence. Only in the self can the drama of truth occur.
Yet when the Existentialist looks inside himself, what does he find? Nothing. Looking back beyond birth or forward beyond death, he sees the void; looking into his own center, thrusting aside all knowledge, all memory, all sensation, he sees the chasm of the ego, formless and inconceivable, like the nucleus of an electron. And he is led to ask, as philosophers throughout history have asked: why is there anything instead of nothing, why the world, the universe, rather than a void? By concentrating all attention on this nothing within himself and underlying the objective surface of reality, he gradually transforms nothing into the concept of Nothingness, one of the truly great accomplishments of human sensibility. Nothingness as a force, a ground, a reality —in a certain sense the reality. From this comes man’s despair, but also, if he has courage, his existential integrity.
From this comes, too, the Existentialist’s opposition to humanism. Not that he is inhumane; quite the contrary, his entire preoccupation is with the sanity and efficacy of the individual person. But he insists that men must confront Nothingness. In a universe grounded in Nothingness, the anthropocentric vision of reality that characterized rational humanism from the Renaissance to the nineteenth century is clearly untenable. Mankind, instead of being the central figure on the stage of reality, the rational creature for whom the nonrational world exists, is actually an accident, a late and adventitious newcomer whose life is governed by contingency; and the proof, paradoxically, comes from rationalism itself, from the Darwinian idea of evolution. Whatever may be the case with trees and stones and stars, man the thinker is a by-product, a nonessential component of reality, and he and all his works cling to existence with a hold that is tenuous and feeble.
Beyond this, generalities must cease. Each of the great Existentialist thinkers pursues his separate course toward the re-establishment of the individual person in the face of Nothingness and absurdity. Sartre is only one of them. But clearly Existentialism, the confrontation with anguish and despair, is a philosophy of our age.