WHEN DEREK BOK last week stood up to welcome the Class of '85 to Harvard, he could just as easily have been welcoming the Class of '84, or '83, or '82. Further than that our institutional memory does not stretch, but at least for four years his message--and that of Matina Horner--has stayed much the same Not even the jokes change.

Two weeks earlier, in marked contrast, Yale President A. Bartlett Giamatti welcomed his new students with a speech denouncing the Moral Majority as a threat to pluralism. Though his target was safe--it is easy to blast Jerry Falwell six months after his peak--the press coverage of Giamatti's address was a reminder of the power of the name of Yale, and presumably, therefore, the name of Harvard. It was refreshing for once to see the power of that name put to such use, but it was even more refreshing to see the president of a prestigious university speaking his mind. It is not, after all, a common sight, at least around Cambridge.

We urge Bok to follow Giamatti's lead, and when the occasion presents itself to speak out on the major issues of the day. In the past Bok has confined his pronouncements to matters of higher education in general and Harvard in particular, arguing that to go beyond that focus is not his job. But Giamatti is right in his idea that the university cannot be cordoned off from society; a threat to pluralism in the real world, for example, is a threat to pluralism in the academic community as well.

More than likely, we will disagree with much of what Bok might choose to say. But that is all right; he speaks, of course, only for himself. And when we differ, both sides are better off knowing precisely where the other stands. It is not as if an activist presidency would be a break with Harvard's past; at least from the days of anti-imperialist President Eliot, Harvard's leaders have been involved in the world around them.

Silence, we fear, affirms the status quo. If Bok likes things the way they are, let him say so. And if not, like Giamatti, let him say so as well. Even if few outside Cambridge pay attention, Bok will spur intellectual debate on campus. And that, after all, is one of the educator's highest goals.