Kernan earned a BA in English from the University of Pennsylvania, Philadelphia, in 1965. He is self-taught as a photographer.
Since 1975 he has been a faculty member at the New School for Social Research in New York City, and from 1973 to 1978 he taught at Manhattanville College, Purchase, New York. He conceived and was associate producer for "To America," a CBS-TV special, in 1976.
One day he noticed an old book on the table in front of him, and in a moment of inspiration, Kernan pulled out four Japanese rocks and placed them on the book. To him it looked like a poem itself - perhaps a haiku, perhaps free verse. He took a photo of the poem and began the series that turned into The Secret Books, photographs of old books juxtaposed against light and objects such as a mirror, a dried bouquet of violets, and a hand with water. He nailed a book, painted over one completely, created a text out of ants, and bound one in steel bars.
His work has been shown around the world, from the Whitney Museum in New York City to the Museum of Photography in Greece, even appearing in the Biblioteca Alexandrina in Alexandria, Egypt and he has appeared in The New York Times Magazine, Communication Arts, Graphis, and the Atlantic Monthly.
A member of ASMP. Keman won a fellowship from the Eugene O'Neill Foundation in 1968.