THE experience of recent weeks has convinced me that traditional divestment protests will never change Harvard's investment policies. We have tried rational argument. We have tried massive expressions of student opinion. None of these has worked.

The time has come for Harvard students to adopt stronger, more visible and more disruptive tactics to persuade Harvard to sell its remaining stock in companies that do business in South Africa.

During a recent meeting between President Derek C. Bok and four members of the Undergraduate Council's Ad Hoc Committee on Divestment, I became convinced that nothing else would work to achieve our goals.

We on the committee had planned to present Bok with a list of student signatures on a petition supporting divestment. As we talked, Bok noticed the petition and told us that he would not care even if we had 6000 students' signatures on a petition. Only rational arguments, he said, could convince him to support divestment.

He continued by saying that we did not have any rational justification for divestment, citing the 1986 council report on divestment as an example of the type of well thought-out position that current activists lack.

The implications of Bok's statement surprised me. I had expected him to say that he could understand the students' views on divestment, or at least that he was sensitive to student concerns. Instead, he categorically dismissed those students who support divestment and claimed that their arguments lacked rational justification.

Bok either failed to realize or just ignored that the arguments for divestment made in 1986 are just as valid in 1990. The divestment movement has used the 1986 report as an intellectual basis for its ongoing activism.

Bok's comments at the meeting have forced me to significantly reconsider the current strategy for encouraging Harvard to divest. The traditional tactics of rallies, letter-writing campaigns and petitions have not worked. What else can be done?

I DECIDED that the ad hoc committee should write another report, updating the conclusions and reaffirming the principles of the 1986 report. We are currently working on this project.

But this alone will not persuade Bok and the Corporation to divest. After all, the comprehensive, well-argued Undergraduate Council report of 1986--presumably the type of "rational argument" that Bok wants--has yet to change his mind.

It is doubtful that an updated version will be any more effective. Bok simply used the issue to keep divestment activists running around in circles while Harvard continues to hold stock in companies that do business in South Africa.

We have offered plenty of rational arguments for divestment: the vast majority of South African opposition leaders call for the international isolation of South Africa. Many of them, including Archbishop Desmond M. Tutu, specifically call upon Harvard to divest. Isolating South Africa has worked to effect positive change. Harvard's divesting will add significantly to that isolation. Divestment will not affect the quality of education at Harvard, and so on, ad nauseum.

Unfortunately, these arguments carry little weight with the Corporation, because the fundamental disagreement between proponents and opponents of divestment is not over factual calculations, but moral values.

The Corporation believes that some companies doing business in South Africa are better than others, and thus pursues a policy of "selective divestment." Supporters of divestment believe that it is inherently reprehensible to invest in any company that does business in such a racist and repressive society.

On this moral disagreement, rational persuasion doesn't carry much weight, because it is the Corporation--hardly an impartial judge--that decides which arguments to accept.