David Hawkins, a philosopher of science who was an assistant to J. Robert Oppenheimer when he directed the Manhattan Project to build an atomic bomb and the official historian of the project, died on Feb. 24 2002 at his home in Boulder, Colo. He was 88. After the project, of which he was later very critical, he spent the balance of his life teaching and writing about the philosophy of science and training teachers in the education of children in science and math. He received a MacArthur Foundation ''genius'' grant in 1986, the first year of the awards, for work in philosophy and childhood science education. David Hawkins was born on Feb. 28, 1913, in El Paso, the youngest of seven children of William Ashton Hawkins, a railroad lawyer and a founder of the city of Alamogordo, N.M., and Clara Gardiner Hawkins. He attended the Hotchkiss School in Connecticut, leaving after his junior year to enroll at Stanford University, where he majored in philosophy. After receiving a B.A. in 1934 and an M.A. in 1937, he went to the University of California, earning a Ph.D. in probability theory in 1940.