A professor of media ecology, Postman first gained national attention with the book "Teaching as a Subversive Activity," a critique of rote learning and other traditional education methods, which was co-written with Charles Weingartner and published in 1969.

He later focused his wry intelligence on technology, most notably television and computers, offering a cautionary perspective that caused some critics to regard him as something of a Luddite.

His best-known books in this vein include "Amusing Ourselves to Death: Public Discourse in the Age of Show Business" (1985), "The Disappearance of Childhood" (1994) and "Building a Bridge to the 18th Century" (1999).

Postman avoided computers; he wrote all of his books in longhand, generally over bagels and coffee at a favorite diner in Queens. He did not use a cell phone; he did not e-mail. He was probably, by his own proud admission, "one of the few people that you're likely to ever meet who is opposed to the use of personal computers in school."

He even spurned the cruise-control option when he bought a new car. "What is the problem to which this is the solution?" he asked the bewildered car salesman, popping the question he had used countless times in his seminars to challenge students.

The car salesman mustered a reply after a moment, suggesting that cruise control was for people who had trouble keeping their foot on the gas pedal. In his many years of driving, Postman countered, stepping on the gas had never been a problem. In his view, there usually was no good answer to his searingly simple question. He always followed up with another zinger: "Are you using the technology, or is it using you?"

"He didn't care if you had a better solution to a problem he never felt was real, and he would make fun of you if you tried to recommend it," NYU journalism professor Jay Rosen, who studied under Postman, said in an essay posted Friday on the Internet magazine Salon.

"I am not a Luddite," Postman once told a Canadian interviewer. "I am suspicious of technology. I am perfectly aware of its benefits, but I also try to pay attention to some of the negative effects."

Postman, a New York native, was educated at the State University of New York at Fredonia and at Teachers College at Columbia University, where he earned a master's degree and a doctorate in education. He began teaching at NYU in 1959, and in 1971 founded its media ecology program to study how modes of communication affect human perception and interaction.

His survivors include his wife of 48 years, Shelley Ross Postman, two sons, a daughter, four grandchildren, a brother and a sister.

Early in his career, Postman made a name for himself as a radical education reformer, in the same league with Jonathan Kozol and John Holt, practitioner-theorists who advocated wholesale changes in the structure of schools. "Teaching as a Subversive Activity" said schools stymied real education by insisting that students memorize trivial facts and by presuming there was only one right answer to any question.

"Subversive" schools, in the Postman sense, would not rely on multiple-choice tests or textbook lessons. He favored an "inquiry-based" approach that emphasized the process of learning by encouraging students to ask their own meaningful questions.

The teacher's goal would be to develop "a new kind of person, one who — as a result of internalizing a different series of concepts — is an actively inquiring, flexible, creative, innovative, tolerant, liberal personality who can face uncertainty and ambiguity without disorientation."

The book became a 1960s classic, and is still in print.

Ten years later, however, Postman stopped talking about blowing up old definitions of schooling and began embracing many of its conventions. In "Teaching as a Conserving Activity," also co-written with Weingartner, he advocated dress codes for teachers and students and emphasized the importance of helping poor and minority youths become competent in standard English. Society had become so unsettled by 1979, when the book was published, that Postman believed it was necessary for schools to become a stabilizing, or conserving, force.

The social revolutions of the 1960s and '70s were one factor in Postman's apparent philosophical reversal. But the most salient influence was television's cultural ascendance. The electronic medium had become "the command center" of American society, he said, and this was not good news.

Postman was a student of Marshall McLuhan, the Canadian media critic famous for his warning that "the medium is the message." Television, Postman argued, was antithetical to inquiry and it stunted critical thinking. It told children too much and blurred the lines between childhood and adulthood. These became the primary notes of a lament that he sounded for the next two decades.

"TV serves us most usefully," he wrote in "Amusing Ourselves to Death," "when presenting junk-entertainment; it serves us most ill when it co-opts serious modes of discourse — news, politics, science, education, commerce, religion."

Postman did watch television; he was a fan of history and sports programs and old movies. What disturbed him most was TV news, which he believed bred intellectual dullness by turning viewers into passive spectators. "In Russia, writers with serious grievances are arrested," he wrote, "while in America they are merely featured on television talk shows, where all that is arrested is their development."

He was a fan of CBS' "Late Night" host David Letterman, primarily because much of Letterman's humor deflated the media, such as his satirical "man on the street" interviews that exposed the absurdities of TV reality. Letterman, Postman once said, "tries to 'break the frame' of the television screen. That is really the most important task for schools today — to break the screen for the youngster."

He was adamant that schools should help students discern how technology molds thinking and communication and teach them to view TV and computers not as tools but as philosophies of knowledge.

Postman may have been one of the few prominent critics of "Sesame Street," the pioneering educational television show for preschoolers who learned their ABCs and numbers from warm, fuzzy characters and cartoons with catchy music. Although many experts would disagree with his contrarian assessment, Postman maintained that the show, in pandering to the appetite for entertainment, taught children not to love school, but to love TV.

"We now know that 'Sesame Street' encourages children to love school only if school is like 'Sesame Street,' " he told The Times in 1988.

The media critic "had tremendous respect for television as one of the greatest forms of entertainment," said Terrence Moran, a former student of Postman and an NYU colleague. "His rap against 'Sesame Street' was that the structure was the same as a commercial. It doesn't matter what the content is. The medium — the structure — is what is important."

Postman's most powerful idea was that "the media are not merely transmitters of information but environments in which cultures grow," Moran said. "He was always interested in how the structure of communications systems shaped people."