The author of 17 books translated into 32 languages, she vaulted to public attention and critical acclaim with the 1964 publication of "Notes on Camp," written for Partisan Review and included in "Against Interpretation," her first collection of essays, published two years later.
Sontag died at Memorial Sloan Kettering Cancer Center in New York City.
Sontag wrote about subjects as diverse as pornography and photography, the aesthetics of silence and the aesthetics of fascism, Bunraku puppet theater and the choreography of Balanchine, as well as portraits of such writers and intellectuals as Antonin Artaud, Walter Benjamin, Roland Barthes and Elias Canetti.
Sontag was a fervent believer in the capacity of art to delight, to inform, to transform.
"We live in a culture," she said, "in which intelligence is denied relevance altogether, in a search for radical innocence, or is defended as an instrument of authority and repression. In my view, the only intelligence worth defending is critical, dialectical, skeptical, desimplifying."
In a Rolling Stone article in 1979, Jonathan Cott called Sontag a writer who was "continually examining and testing out her notion that supposed oppositions like thinking and feeling, consciousness and sensuousness, morality and aesthetics can in fact simply be looked at as aspects of each other — much like the pile on the velvet that, upon reversing one's touch, provides two textures and two ways of feeling, two shades and two ways of perceiving."
A self-described "besotted aesthete" and "obsessed moralist," Sontag sought to challenge conventional thinking.
She wrote four novels, "The Benefactor," "Death Kit," "The Volcano Lover," and "In America," which won the 2000 National Book Award for fiction.
Sontag was born Jan. 16, 1933, in New York City and raised in Tucson and Los Angeles, the daughter of an alcoholic schoolteacher mother and a fur trader father who died in China of tuberculosis during the Japanese invasion when Sontag was 5. She was a graduate of North Hollywood High School and attended UC Berkeley and the University of Chicago — which she entered when she was 16 — and Harvard and Oxford.
In 1950, while at the University of Chicago, she met and 10 days later married Philip Rieff, a 28-year-old instructor in social theory. Two years later, at age 19, she had a son David, now a prominent writer. She was divorced in 1959 and never remarried.
Sontag was reading by 3. In her teens, her passions were Gerard Manley Hopkins and Djuna Barnes. The first book that thrilled her was "Madame Curie," which she read when she was 6. She was stirred by the travel books of Richard Halliburton and the Classic Comics rendition of Shakespeare's "Hamlet." The first novel that affected her was Victor Hugo's "Les Miserables."
"I sobbed and wailed and thought [books] were the greatest things," she recalled. "I discovered a lot of writers in the Modern Library editions, which were sold in a Hallmark card store, and I used up my allowance and would buy them all."
She remembered as a girl of 8 or 9 lying in bed looking at her bookcase against the wall. "It was like looking at my 50 friends. A book was like stepping through a mirror. I could go somewhere else. Each one was a door to a whole kingdom."
Edgar Allan Poe's stories enthralled her with their "mixture of speculativeness, fantasy and gloominess." Upon reading Jack London's "Martin Eden," she determined she would become a writer. "I got through my childhood," she told the Paris Review, "in a delirium of literary exaltations."
At 14, Sontag read Thomas Mann's masterpiece, "The Magic Mountain." "I read it through almost at a run. After finishing the last page, I was so reluctant to be separated from the book that I started back at the beginning and, to hold myself to the pace the book merited, reread it aloud, a chapter each night."
Sontag began to frequent the Pickwick bookstore on Hollywood Boulevard, where she went "every few days after school to read on my feet through some more of world literature — buying when I could, stealing when I dared."
She also became a "militant browser" of the international periodical and newspaper stand near the "enchanted crossroads" of Hollywood Boulevard and Highland Avenue, where she discovered the world of literary magazines. She was fond of recounting how, at 15, she had bought a copy of Partisan Review and found it impenetrable. Nevertheless, "I had the sense that within its pages momentous issues were at stake. I wanted desperately to crack the code."
At 26, she moved to New York City where, for a time, she taught the philosophy of religion at Columbia University. At a cocktail party, she encountered William Phillips, one of Partisan Review's legendary founding editors and asked him how one might write for the journal. He replied, "All you have to do is ask." "I'm asking," she said.