Politically, Cousins was a tireless advocate of liberal causes, such as nuclear disarmament and world peace, which he promoted through his writings in Saturday Review. In a 1984 forum at the University of California, Berkeley, titled "Quest for Peace", Cousins recalled the long editorial he wrote on August 6, 1945, the day the United States dropped the atomic bomb in Hiroshima. Titled "The Modern Man is Obsolete", Cousins, who stated that he felt "the deepest guilt" over the bomb's use on human beings, discussed in the editorial the social and political implications of the atomic bomb and nuclear power. He rushed to get it published the next day in the Review, and the response was considerable, as it was reprinted in newspapers around the country and enlarged into a book that was reprinted in different languages.
Cousins was portrayed by actor Ed Asner in a 1984 television movie, Anatomy of an Illness, which was based on Cousins's 1979 book, Anatomy of an Illness as Perceived by the Patient: Reflections on Healing. Cousins was not pleased with the commercial nature of the movie, and with Hollywood's sensationalistic exaggerations of his experience. He and other members of the Cousins family were also taken aback by the casting of Asner, due to the fact that the two men bore scant physical resemblance to each other. But Asner tried faithfully, Cousins felt, to convey the spirit of his subject, and once the film was completed, Cousins was said by Asner to look upon the movie with a certain degree of tolerance, if not with delight.