Coming as it does after Nichols’s Who’s Afraid of Virginia Woolf?, The Graduate, and Catch-22, there is a danger, I’m afraid, that Carnal Knowledge will be found disappointing by those who feel that a man’s movies must be increasingly elaborate and long-focused if it’s to be said that his career is progressing. This is just a variation on the old Hollywood myth to the effect that unless each succeeding film of an individual director is more expensive, and a bigger box-office success than the one before, the director must be on his way to Skid Row, or even retirement in Santa Monica.
Carnal Knowledge is nothing if not short-focused. Indeed, it’s virtually a two-character film that devotes itself—with an exclusivity that is rare outside stag films, television commercials, and Japanese haiku—to a single subject: the sexual disasters of Jonathan (Jack Nicholson) and Sandy (Art Garfunkel), initially met when they are Amherst undergraduates in the 1940’s, and finally abandoned as they enter bleak middle-age in the 1970’s.
— Bosley Crowther, from his July 1, 1971 New York Times review