Was Ronald Reagan telling the truth two weeks ago about the Nicaraguan government -- that it is "totalitarian, brutal and cruel"? Was he telling the truth in 1984 when, in a run of public statements, he described Nicaragua as everything from "a totalitarian dungeon" to a land seized by "a communist reign of terror"? The government, he said, staged "Soviet-style sham elections."

No other country in the world has been singled out for such obsessional and intense abuse by Reagan. For a brief time, he was off the edge about the Soviet Union, but his "evil empire" harangues have stopped. There appears to be no letup on Nicaragua. He peers at it with malignity and looks not at all for truths that might temper the damnations.

A world leader is reducing himself to ceaseless diatribe. A pathetic spectacle is on display. Nicaragua under the Sandinistas has had failures and abuses. Groups like Americas Watch and Amnesty International have reported on breakdowns in press freedom, due process and the rights of prisoners and minorities. None of that has made the Sandinista government totalitarian, brutal or cruel. Its officials are not dungeon masters.

Nor has anything happened in revolutionary Nicaragua to put it close to the violence and corruption found in El Salvador or Guatemala. Massacres of civilians that have routinely occurred in the past five years in those army-dominated countries have not bloodied Nicaragua. Institutionalized killing ended with the fall of the U.S.-supported 43-year Somoza dynasty in 1979.

The attacks by Reagan on the Sandinistas are not based in truth, which is bad enough. But they are so poisonously one-sided that no recognition of the social achievements of the past five years is allowed into the discussion. The Committee for Health Rights in Central America, a San Francisco-based group, reports that health improvements in Nicaragua are unprecedented.

* For the first time, public eye clinics have been established.

* In 1979, Nicaragua had 37 hospitals. Seventeen new ones were opened by August 1984.

* The number of medical students has more than tripled in five years, from 150 before 1979 to 550 in 1984.

* Infant mortality was 120 deaths per 1,000 live births under Somoza; now it has dropped to 58 per 100,000.

The last fact represented such a rare breakthrough that in 1982 the World Health Organization and the United Nations Children's Fund gave their award to Nicaragua for the best health achievement in a Third World nation.

Few American physicians are as dedicated to Nicaraguans, or as knowledgeable about advances being made by the Sandinista government, as Dr. John Bresette, a Washington urologist. He is a regular visitor to Nicaragua and pays his own expenses. The health breakthroughs are there, he says, "but the needs are still tremendous." He tells of doctors not having enough surgical gloves and operating rooms lacking light bulbs.

Bresette has come to love Nicaraguans for what he calls "their tremendous desire to improve. I've never been to a communist country, but from what I understand they are ruled by atheistic regimes, the party members can't belong to a church, there is no freedom of movement for visitors, and the local people are afraid to talk with you. None of that -- absolutely none -- is true in Nicaragua. It is a Catholic country. Priests are in the government. Pluralism is at work. Reagan's tirades mock the reality that I have seen."

There is continuity in Reagan's venomed hate of Nicaragua. It is another imposition of American views on a comparatively poor and powerless country. The traditional role for the United States in Nicaragua has been as caller of the shots. The Somoza dictators were our dictators, just as today the counterrevolutionary "contras" are our counterrevolutionaries. Reagan praises the latter as "our brothers." In 1979, Reagan publicly scolded the Carter administration for withdrawing economic aid to Somoza: "This we are doing because, according to the State Department, President Somoza is in violation of our standards of human rights. He may be -- I don't know."

Was it that Reagan didn't know or didn't want to? It is the same question now. It is impossible to imagine that he doesn't know more than his recent insults suggest, that Nicaragua is anything but a "totalitarian dungeon." Deliberate ignorance about the murderous Somoza was as intellectually dishonest in 1979 as the current deliberate ignorance about the Sandinista reforms is dangerous now.