Ray Hooker is a member of the Nicaraguan National Assembly who happened to be in town last week when President Reagan announced that the Sandinistas must say "uncle" to avoid his wrath. Hooker did not appreciate having the president compare Nicaragua's "contras" to Simon Bolivar, the great South American liberator; he was a captive of the contras for almost two months and found Reagan's comparison "degrading."

Hooker, an imposing, bearded, slow-spoken man, was captured Sept. 5 by Indian guerrillas when the speedboat in which he and two others were riding broke down. Hooker tried to escape by jumping into the water, but he suffered a bad wound in his side and was captured. The Indians claim he was carrying an AK47 rifle; he denies it.

Hooker's release came after an October meeting in New York -- arranged by Sen. Edward M. Kennedy (D-Mass.) -- between Daniel Ortega, who has since been elected president of Nicaragua, and Hooker's captor, Brooklyn Rivera, leader of the Miskito Indian rebels, who are fighting for autonomy. Hooker is on the commission appointed by the Sandinistas to bring about peace with the Miskitos. The Sandinistas now admit they wronged the Indians and are trying to make amends.

Hooker, who was elected to the National Assembly two weeks after his release, is in this country to tell the Sandinista story on 20 campuses, including Harvard, Stanford and his alma mater, Ohio University, which led a letter-writing campaign for his release. Hooker earned degrees in history and education from Ohio in 1967, and its current and past presidents wrote the Senate Intelligence Committee in his behalf. So did some other academics and officials of the Moravian Church, in which he grew up.

"I was basically left to die," Hooker says of his first days with the guerrillas. "When I didn't, they thought it was the will of God. Also, I was something like Scheherazade, I told them stories about the history of the Atlantic coast of Nicaragua. And I knew some of them; I grew up with them and it was much more difficult for them to harm me. I read to them from the Bible, the only book in camp. Most of them are illiterate."

His companions did not fare so well. Patricia Delgado, an official of the regional government, and Santiago Mayorga, the speedboat's pilot, were beaten, Hooker says.

He says he resents the president calling his captors "our brothers."

And he has a warning for the White House, in case it is considering invading Nicaragua:

"We can stand pressure. We have been fighting for a long time. We live life intensely. For the first time we are making decisions regarding our own future. Hundreds of thousands of Nicaraguans will fight to the death.

"We don't want to be a military base or another Cuba. The U.S. has legitimate security concerns. We are not a Soviet state. Up until July 1979, you could not speak about Marx without going to prison. We want to be a pluralistic society in which all ideologies are respected," he says.

The response to Hooker's capture illustrates one of Reagan's problems. Many Americans know Nicaragua and the players for themselves, and do not take Reagan's word for it that its government is "cruel" and "brutal."

"It's not like Vietnam," says Thomas Walker, a political science professor at Ohio University who got the ball rolling for the Hooker protest. "People here have been back and forth for years."

Walker worries that even though Reagan realizes how bloody an invasion could be, he is investing so much ego and prestige in molten rhetoric that the idea will acquire momentum.

It is different in another way from Vietnam: Today's campus youth seems ready to defend "freedom" as defined by Reagan.

Reagan may be trying to stampede Congress into giving him $14 million for the contras. Many legislators have meekly accepted his premise that pressure on the Sandinistas must be maintained.

Some put it to the advent of hard-nosed Patrick J. Buchanan to the president's inner circle. As an adviser to President Richard M. Nixon in 1969, Buchanan counseled that Nixon need not end U.S. involvement in Vietnam at once -- public opinion, he argued, could be rallied round the POWs. In his late newspaper column, Buchanan demanded that the Sandinistas be "cauterized or cut out" like a cancer.

Nothing has really happened in the two years since the president "went to the people" and denied seeking the overthrow of the Sandinistas. The contras have captured no territory and continue to war among themselves. Public enthusiasm for war has not increased.

The only thing that has happened was the November election. Maybe a man who wins 49 states thinks he won an emperor's prerogative to run the world.