Circuit Court Judge Antonin Scalia, President Reagan's choice for associate justice of the United States Supreme Court, will not attend today's 350th celebration symposium on the Constitution as planned.

A spokesman for Scalia said that the associate justice designate, who has been approved for a Supreme Court post by the Senate Judiciary Committee but has yet to be confirmed by the full Senate, decided to cancel because of his "decision not to make appearances or give speeches during the confirmation process."

The 106 academic symposia, which were planned more than a year ago, have suffered a handful of other cancellations. Carlo Rubbia, Nobel prize-winning professor of physics at Harvard, has a scheduling conflict and will not attend Saturday's symposium entitled "Ultimate Physical Theories," according to James Quitslund '63, who oversees the 350th symposia sponsored by the Faculty of Arts and Sciences.

Quitslund said at least one other panelist will not participate in the symposia as scheduled. He said there were no plans to compile or publish a list of such changes in the roster of academic stars who have agreed to take part in the presentations, which are designed for layman alumni.

Scalia, a 1960 graduate of the Law School, wasto have taken part in a symposium entitled"Contrasting Approaches to the Interpretation ofthe United States Constitution," which promises toprovide a high-powered forum on the direction theSupreme Court should take in the future.

Although the circuit court judge was slated toserve on the panel since early last spring, thesymposium became one of Harvard's hottestofferings when Reagan in July nominated him toreplace William H. Rehnquist as associate justice.Rehnquist was simultaneously nominated to succeedformer Chief Justice Warren Burger.

The symposium now includes Loeb UniversityProfessor Emeritus Archibald Cox '34 and TylerProfessor of Law Laurence Tribe '62, who was avocal opponent of Reagan's decision to nominateRehnquist for Chief Justice. Other participantsinclude Fairchild Professor of Law Andrew L.Kaufman '51 and Georgetown Law Professor MarcKushnet