A controversial spokeswoman for the peace movement

Norman Cousins, former editor of Saturday Review, adjunct professor in the School of Medicine at University of California at Los Angeles, and author of the newly published ``Albert Schweitzer's Mission: Healing and Peace'' (W. W. Norton), discovered an unusual brand of philanthropy in California. Here he tells of Joan Kroc's contributions to peace. A favorite conversation piece at West Coast dinner tables these days is Joan Kroc, widow of the founder and owner of the world's largest chain of hamburger and fast-food restaurants. What excites the growing curiosity about Joan Kroc is not just that she is listed by Forbes magazine as one of the wealthiest women in America but that she is using her personal fortune in ways not generally associated with the rich and the mighty. In one short year, Joan Kroc has become perhaps one of the most powerful figures in the American peace movement.

Joan Kroc's name first came to national attention in March 1984, after the mass tragedy in San Ysidro, near San Diego, when a deranged James Huberty stepped into a MacDonald's restaurant and sprayed bullets in every direction, leaving 21 dead. Joan Kroc organized a fund for the relief of the families of the murdered and wounded, contributing an initial $100,000.

In the past few weeks, Joan Kroc has been giving the sports writers ample material for controversy. As owner of the San Diego Padres, the National League baseball club and pennant winner in 1984, she reversed the decision of Ballard Smith, the president of the club, who happens to be her son-in-law. Smith decided to unload Dick Williams as manager of the club without consulting Kroc. Having previously assured Williams of her complete support, Kroc honored the commitment by rehiring the man who had given the people of San Diego a pennant-winner. The idea of a woman making major decisions for a big-league ball club did not sit easily with some of the sports writers of the area. But Kroc held fast and a groundswell of support has developed behind her. The net effect of the episode has been to make her good newspaper copy.

The news media have discovered that Joan Kroc is a great deal more than a very pretty lady with a lot of money. She parries the thrust of interviewers with knowledgeable answers and good-natured wit. They learned of her work across the nation in combating alcoholism and drug abuse. It became known that she was an accomplished musician, having played the organ and piano professionally. It also became apparent that she read widely and was well-informed on national and world affairs.

Those who follow these reports are not surprised, therefore, when they pick up their newspapers and see full-page newspaper advertisements calling for arms control. For example, on May 30 of last year she bought space in the country's major newspapers to give prominence to a quotation by President Dwight D. Eisenhower on the need for people to prod their leaders to put an end to the arms race. It was estimated that the advertisement cost Joan Kroc something in the order of $400,000.

The favorable public response to the newspaper advertisement led Joan Kroc to return with a second message -- again in the form of full-page newspaper advertisements. This time the message attempted to dramatize graphically the amount of nuclear explosives accumulated in the arsenals of the United States and Soviet Union. The advertisement conveyed the idea that the US already possessed sufficient nuclear firepower to burn off every city in the world, with enough left over to repeat the performance a dozen times. The advertisement also made the point that the Soviet Union was not far behind.

It was emphasized that what was being advocated was not unilateral disarmament but rather serious efforts in the direction of responsible and enforceable control of nuclear force.

Joan Kroc's newspaper advertisements as well as her other activities have been variously interpreted. In some quarters, her peace efforts were regarded as an attempt to strengthen the hand of President Reagan in his arms control negotiations with Premier Gorbachev. There were strong hints, unsubstantiated, that the White House had been looking for exactly the kind of public prodding that Joan Kroc had been supplying.

By contrast, Joan Kroc has been criticized as a soft-headed stooge for the Soviet Union. Calvin Thomas, a paid publicist for the Liberty Federation (Moral Majority), wrote a newspaper column attempting to ridicule Kroc for presuming to take stands on public affairs. One of the newspapers published Thomas's column under the headline: ``Joan Kroc Should Get Back in the Kitchen.'' This was all that was required to stir up the feminists, one of whom, in a letter-to-the-editor, wrote that Thomas was a typical macho male who believes women are good for breeding and cooking and little else.

The Thomas column boomeranged in another direction. In addition to those who were offended by the poor taste of the piece were those who felt that Thomas was actually hiding behind Kroc's skirts to attack Reagan supporters and members of the White House staff for endorsing serious negotiations with the Soviet Union on issues of arms reduction and control.

Joan Kroc has taken the attacks on herself philosophically. ``I may be a Joannie-come-lately to world issues,'' she has said, ``but all that means is that I have to make up for lost time. Anyway, the problem is big enough so that no one need apologize for trying to take a piece of it. We've all got investments to protect. I've got a lot to protect -- not just the fortune left to me by Ray but four wonderful grandchildren. If nuclear war should come, everyone will die poor. My daughter Linda has started a movement that's catching on. It's called MEND -- Mothers Embracing Nuclear Disarmament. I couldn't be prouder. I tend to think we will all be judged by our respect for the rights of the next generation and all the generations to come.''

What is Joan Kroc up to next? ``A lot of people are involved in this effort,'' she has said. ``It oughtn't be hard to find a way to help them.''