American businesses should stay in South Africa because they create a "ripple effect" that improves the lives of Blacks, an official of the firm that rates companies on their adherence to the Sullivan Principles told a Center for International Affairs audience yesterday.

"If you divest, you put yourself in a position where you have no leverage to do anything," said I. Reid Weedon, senior vice president of the Cambridge consulting firm Arthur D. Little. The firm rates companies on how well they are adhering to the principles, a set of voluntary measures to desegregate workplaces and provide greater advancement opportunities for South Africa's Black majority.

While activists at Harvard have for 13 years called on the University to sell its $400 million of stock in companies that do business in the apartheid state, Weedon said those firms are the most active force for constructive change within South Africa.

Weedon said he meets with Harvard officials to review the University's portfolio every year when the new Sullivan ratings are issued, and said Harvard doesn't invest in any companies which failed to get a passing grade from ADL.

Because past guidelines have been so successful, Weedon said, "The workplace issues are sort of passe at this stage," and new Sullivan guidelines have been issued which require a company to actively combat apartheid.