SPEAKING at Class Day here a year ago, Tom Wicker, associate editor of The New York Times, called the wealth gap between rich and poor a major cause of violence and social unrest in this country.

"We in America are not going to escape much longer the meaning and consequences of the situation in which just one per cent of our total population holds 28 per cent of the net wealth of this country with all the other 99 per cent and the public sector scrambling for what is left," he said.

Nor could we comfortably ignore much longer a situation in which the poorest fifth of the nation receives only 4 per cent of the nation's annual income, and the next poorest fifth, only 11 per cent, while the richest fifth gets about 45 per cent.

Out of self-interest alone, Wicker said, the relatively privileged members of his Harvard audience ought to "stand in the years to come for something nearer to equality--equality in material things--something nearer to equality for the poor, and something closer than what we have now, in my judgment, to individual liberty and justice for all of us," for this is what would be required to "alleviate many of the social tensions that have plagued our lives in recent years."

Ironically, shortly before Wicker spoke at Harvard, income redistribution died as an issue of the 1972 Presidential campaign. It died in California when Hubert Humphrey knocked the political life out of George McGovern's proposal to give $1000 to every person in the United States.

McGovern's plan would not actually have given equal benefits to everyone, rich or poor, though it might have appeared that way. The plan would have provided a minimum income of $4000 to a family of four with no income and progressively diminishing amounts to families with incomes up to $12,000 a year.

Beyond this point, the plan would have taxed back the total amount of the income grants. But, until a family of four's income reached $20,000 or so, it would still be paying lower net taxes than it does at present. Only beyond this point would its taxes increase. Thus, higher taxes at higher income levels would pay for lower taxes--and positive income supplements--at lower levels.

After the California primary, McGovern withdrew his proposal for further study. When he presented his new welfare reform proposals almost three months later, his earlier commitment to supplementing the incomes of working people--poor and not-so-poor--was gone. Throughout the campaign, McGovern stood fairly firm on tax reform--taking money from the rich--but after California, he offered less of that money to the poor and none to the middle class. His advocacy of total reform had given way, or so it seemed, to the requirements of political reality.

HOW DID McGovern come to make his $1000 per person proposal in the first place and why did he draw back from it later? A closer look at these questions may throw some light on the political pitfalls, avoidable or unavoidable, involved in advancing a complicated economic reform proposal of this sort.

A political judgment lay behind McGovern's initial decision to make his minimum income proposal--but it was a judgment tied to the political situation before the primaries, not to the situation in which McGovern might find himself as the Democratic candidate or front-runner. In late 1971, McGovern was running far behind Muskie as the party favorite. His main hope was to stand out to the left of the party on the issues and thus increase its support from the left-leaning, issues-conscious wing of the party which was already attracted to him by his stand on the Vietnam war.

McGovern was not alone on the left, however. His monopoly there was challenged by Fred Harris, John Lindsay, and even George Wallace. All, in differing senses, were "populists." "Harris, particularly, and to some extent Lindsay were talking about income redistribution and getting a pretty good play in the press," especially from liberal columnists like Tom Wicker and The Washington Post's David Broder, Frank Mankiewicz, McGovern's top political adviser, recalls.

Columnists like these "have far more impact on a primary than they do in any other time because people only vote in a primary who have an active interest in the campaign," Mankiewicz said. And these columnists were portraying Harris and Lindsay as "guys who were talking about the real issues," an image that McGovern wanted.

Wallace provided a major stimulus for McGovern's stand on tax reform, Mankiewicz said. "Wallace was talking about it [tax reform], but only in terms of what was bad. We thought we could cash in on Wallace unrest by saying 'Wallace talks about this and so do we, but Wallace doesn't say what he'd do about it and we do.'"

The aide responsible for putting together McGovern's tax and welfare reform package was Gordon Weil, who covered the European Common Market for The Washington Post before he came to work for McGovern in 1971.

Weil dates the decision to offer proposals on the tax and welfare issues back to June 1971, when he and McGovern met with a number of liberal economists to work out an economics agenda for the campaign. Tax reform and Nixon's failure to achieve full employment were put at the top of the agenda, but Weil remembers "mention of a need to do something in the welfare reform area."