What was going on when I was born?

The Reagan Administration has decided to offer 15 and possibly more American-built F-16 fighter planes to Pakistan as part of a five-year economic and military assistance package, Administration officials said today. The F-16 jet fighters are being offered to offset the threat believed to be posed by the Soviet military presence in Afghanistan. The offer is being made by Under Secretary of State James L. Buckley, who is in Pakistan to discuss the $2.5 billion aid package previously proposed by the Administration. Officials said that the proposal on the fighters was approved this week at a National Security Council meeting after Mr. Buckley had already left for Parkistan. Objections were raised by the Office of Management and Budget and by the Air Force, the officials said.

Major league baseball's 650 players, engaged in an 18-month-old labor dispute with team owners, struck regular-season games yesterday for only the second time in history. There was no way to determine immediately how much of the season would be wiped out, but there were concerns that the strike would be a long one. ''Every indication is it's a total roadblock, and we don't have any answers,'' Rusty Staub, the New York Mets' player representative, said after a fruitless 30-minute bargaining session at the Doral Inn in Manhattan yesterday morning. Kenneth E. Moffett, the Federal mediator who was instrumental in helping to avert a baseball strike during the regular season last year, said he would not bring the parties together again until Monday or Tuesday. Mr. Moffett said the two sides were ''pretty deadlocked.'' Mr. Staub, Mr. Moffett and principal negotiators spoke 12 hours after Marvin Miller, executive director of the Major League Baseball Players Association, emerged at 12:30 A.M. from a bargaining session that began late Thursday night and announced that the strike was on.

The United Nations Security Council met here this evening in an emergency session on Israel's attack on an Iraqi nuclear reactor. Iraq's Foreign Minister, Saadun Hamadi, accused Israel of ''a clear-cut act of premeditated aggression'' in its raid Sunday against the French-built reactor near Baghdad and urged the Council to call for a halt in military trade with Israel. In reply, Yehuda Blum, Israel's delegate to the United Nations, said his country had ''performed an elementary act of selfpreservation'' in the face of ''a threat of nuclear obliteration'' by an ''implacable enemy.'' The debate that began tonight was expected to reach its climax in a vote on a resolution early next week. A declaration merely condemning Israel might win Security Council approval, but anything stronger would almost certainly face an American veto.

A bill that would require the installation of smoke detectors in more than a million apartments in New York by next Jan. 1 was passed by the City Council's Committee on Housing and Buildings yesterday. The bill, which has been under consideration for two and a half years, is expected to be approved by the full Council on June 30 and to be signed into law by the Mayor in early July. Under the measure, building owners would be required to install detectors in apartments and hotel rooms. But it would not apply to buildings that already have city-approved automatic sprinkler systems in public and private areas.

Lieut. Gov. Mario M. Cuomo, who has been in a public war of words with Governor Carey, but says they have not spoken privately since February, has reactivated his independent campaign committee in preparation for next year's statewide elections. ''I have a committee, I am raising money, I've scheduled a fundraiser,'' Mr. Cuomo said in an interview. ''I know that whatever I do next year, I'll have to run. If you wanted to be Lieutenant Governor, if you wanted to be Governor, if you wanted to be anything, you'd have to run. I'm ready for that.''

The Prime Minister of Poland shuffled his Cabinet today and vowed to crack down on people resisting the party's leadership or engaging in activities against the Soviet Union. Prime Minister Wojciech Jaruzelski announced the dismissal of five ministers and the merging of a number of ministries in what he said was an attempt to streamline the Government and cut back on waste. One of those dismissed was the Justice Minister, Jerzy Bafia, whose prolonged and, so far, inconclusive investigation of police violence in Bydgoszcz angered members of Solidarity, the independent trade union. Deputy Premier Dismissed Another was Deputy Prime Minister Henryk Kisiel, in charge of the Planning Commission. He was apparently held responsibile for not drafting an economic program to overcome the country's problems.

A few days ago, when the Florida Legislature was debating a bill to make it easier for the police to jail juvenile delinquents, a circuit judge, William Gladstone, said he detected in the debate a ''hysteria that wants to lock every kid up.'' The enacted legislation, which turned out to be milder than many officials wanted it to be, was nevertheless one example of how public policy is being changed as a result of a generally aging electorate. Florida's population, according to 1980 census figures released a few weeks ago, is the nation's oldest. Yet in two decades the United States, according to projections by the Census Bureau, will have a similar age-to-youth ratio, with all the conflict and change that that portends. Evidence of the problems that may arise with such change exist here in Broward County, where there are large concentrations of elderly and where intergenerational conflicts have become commonplace. ''All that many older people hear of youth is in connection with delinquency, crime and drugs.'' said Denny Abbott, director of Child Advocacy Inc., part of a national, federally financed organization to help represent young people in legal matters. ''They think the solution is to cordon them off somewhere until they are grown.''

In a rescue drama that brought the President of Italy to this hilly community 12 miles from Rome, a 6-year-old boy who fell into a well three days ago slipped deeper into the shaft last night as rescue workers broke through an adjoining tunnel. Six slightly built volunteers were lowered last night and early today into the parallel tunnel dug by rescuers. Two of them managed to touch the slippery boy, but they were unable to pull him out of the muddy well. ''It's the mud, he's covered with mud,'' one of the volunteers said, shaking his head after coming out of the well without the youngster.

Prime Minister Pierre Elliott Trudeau, who will preside over the summit meeting here next month of seven leading industrial nations, said today that he would seek to force a choice between ''papering over differences'' or seeking basic agreements that would allow the West to ''manage'' political and economic crises in the world. ''I think it will be a difficult summit without assurance of success,'' Mr. Trudeau said at a news conference. He added that it would be ''the first real summit'' because it would deal with basic subjects.

The Quebec government has charged 17 serving or former members of the Royal Canadian Mounted Police with involvement in illegal operations against Quebec separatists in the early 1970's, a Justice Department official said today. Eleven were charged with burglary and conspiracy in the 1973 theft of membership lists of the Parti Quebecois. Six were charged with involvement in two 1972 operations against separatists.

The Taiwan Government is looking toward Peking with greater nervousness than usual. With the arrival there June 14 of Secretary of State Alexander M. Haig Jr., Taipei is anxiously awaiting the first official declarations of the Reagan Administration's China policy. The Government of President Chiang Ching-kuo has waited from Jan. 20 until now for signs of whether and how President Reagan will translate into official action the clear tilt in favor of Taiwan that he expressed in his campaign oratory and throughout his political career. Other than sympathetic remarks - the latest from the President's counselor, Edwin Meese 3d, last month - they have heard nothing from the President since his inauguration.

Leonid I. Brezhnev, the Soviet leader, accused the United States today of having no real interest in entering negotiations on arms controls and of seeking to tilt the European balance of power in Washington's favor.