The success of the National Commission on Social Security Reform in reaching an agreement that The Post generously describes as being "as close to absolute fairness as any Social Security revision can ever be," raises the possibility of further successes, equally important.

This requires some further description of how the agreement came about. Next it will help to recognize how much we needed such a success.

As The Post has reported, it is the judgment of Sen. Bob Dole that the commission was just about resigned to failure when, on Jan. 3, in the course of opening ceremonies of the new Congress, I came over, tapped him on the shoulder and asked: "Are we going to let this commission die without giving it one more try?" The rest of the story has been well reported. What I would like to explain is why I suggested one more try. It is because that morning a newspaper article written by Sen. Dole had suggested that such an effort could succeed. His theme was that the president and the Republican leadership in the Congress were working well together and would continue to do so:

"Social Security is a case in point. With 116 million workers supporting it and 36 million beneficiaries relying on it, Social Security overwhelms every other domestic priority. Through a combination of relatively modest steps, including some acceleration of already scheduled taxes and some reduction in the rate of future benefit increases, the system can be saved. When it is, much of the credit, rightfully, will belong to this president and his party."

Note well: "relatively modest steps." This was the first statement by a prominent Republican leader that the sky was not falling, the system was not "bankrupt," was not a "giant Ponzi scheme," and nationwide "chain letter."

At a meeting of the commission on Dec. 10, Alan Greenspan, the incomparably gifted chairman of the commission, had commented that the problem of Social Security "seems to be unsurmountable, but in reality is not all that big." But the remark was not reported, and in any event it had to come from such as Dole.

There being nothing in Tocqueville to explain this, I will turn to Henry Kissinger, who was wont to break conferences and meetings by declaring: "Agreed. It's a good argument. And it has the further advantage of being true."

Just so Sen. Dole's remark. From the onset of the Social Security crisis, Democrats in the main have agreed--how could we not?--that the system had run into a sharp short-term problem in the aftermath of something that "couldn't happen" and surely was not foreseen, an inflationary recession (roughly during the years 1980-82). But starting in 1990, barring worldwide catastrophe, the system goes into surplus and stays that way for a generation.

The commission proposals will raise or save $169 billion in the seven years 1983-89. At the end of the period there will be, or at least we and the White House project, $100 billion in the Old Age, Survivors and Disability Insurance fund. In other words, the "shortfall" in the short term appears to be in the $60 billion to $70 billion range. Not a small sum, but not an overwhelming one either. Later, new difficulties appear, but as a proportion of gross national product, the actuaries agree that Social Security in 2050--at 5.62 percent--will not be much more than it is today--at 5.16 percent.

All true--and anyone who troubles to read the commission report will find it there. But the truth is only a "further advantage." The decisive issue is the import of the argument.

Social Security, as Sen. Dole wrote, "overwhelms every other domestic priority." The Democrats began Social Security, true enough. But the triumph of the American political system came when the Republicans not only continued it, but expanded it. President Eisenhower added Disability Insurance, and President Nixon added Supplementary Security Income.

After nearly a half-century, the matter had seemed resolved. Then it turned out it wasn't.

There had begun what Sylvia Porter has called "a scare campaign of vicious proportions" to convince the American people that Social Security was a fraud, that they would never get their benefits. (Leaving Blair House Saturday at about 1:30 in the afternoon, I got a cab, explained to the driver what was going on, and was told I was wasting my time, that the Social Security money had been given away as foreign aid. He--age 59-- was sure he would never get any of his promised benefits.)

In 1979, an earlier Social Security commission had a poll done by Peter D. Hart and Associates on attitudes toward the system. To the utter confoundment of those of us who had thought the matter settled, Hart reported that more than half the populace expressed little or no confidence that Social Security benefits would be there when their time came.

Think a moment. Half the population doesn't think it is going to have retirement benefits that are desperately needed by most. Not the cheeriest of thoughts. But think further to what is further implied. That government is lying. That government is stealing. That government cannot be trusted.

That is what the Social Security argument of the past two years has been about. If so large a portion of our people could be brought to believe something so utterly subversive of self- government, we are in trouble indeed. Especially as it was not so.

Then Sen. Dole said as much. Meetings began on our side of the Capitol. Barber C. Conable joined us from the House. Of a sudden the invitation came for all of us to go out to the home of the White House chief of staff, James Baker. By the end of that meeting, it was clear that a long negotiation was ahead, but also what was at stake. Someone had said that what was really involved was our capacity to govern. We begin to accept the idea that there are fundamental issues that our system cannot resolve.

We have got to stop that. There is a center in American politics. It can govern. The commission is just an example of what can be done. First, get your facts straight. Everyone is entitled to his own opinion, but not his own facts. Second, decide to live with the facts. Third, resolve to surmount them. Because, fourth, what is at stake is our capacity to govern.