What was going on when I was born?

President Reagan defended his proposed tax increase today as his aides acknowledged that the Administration's lobbying drive had so far failed to win enough support to insure passage of the measure by Congress. Declaring that it was ''plain hogwash'' to suggest that his legislation called for the largest tax increase in history, Mr. Reagan said the measure was actually ''80 percent tax reform'' and 20 percent tax increase, all of it essential to keeping deficits down. The measure would add $98.9 billion to Federal revenue over three years. ''I would prefer to reduce our budget deficits by continuing to reduce Government spending, and I still think that there is more to be done in that regard,'' Mr. Reagan said in response to a question at a unannounced news conference in the White House briefing room.

Pop music's worst business summer in recent years is drawing to a close, and some insiders in the music industry are saying that an era appears to be ending. Summer concert revenues are down drastically from previous years, pop record sales are a fraction of what they were in the 1970's, and music industry executives are increasingly concerned that young people are taping albums rather than buying them and spending their money on video games rather than on records and concert tickets. CBS Records announced yesterday that it was discharging 300 employees - 15 percent of its professional staff -including several vice presidents, and reducing its regional branch offices from 20 to 10. Robert Altschuler, the company's vice president of press and public affairs, attributed the dismissals and branch reorganization to ''current and projected market conditions.'' 'Real Bottoming-Out' Another insider in the record business said that there had been ''an almost complete lack of business, a real bottoming-out.'' The CBS action is the latest and most severe cutback in a wave that has swept the industry and is expected to continue at other companies.

The Federal Reserve Board yesterday lowered the interest rate that it charges for loans to banks and financial institutions by one-half percentage point in another effort to encourage lower interest rates and stimulate the economy. The reduction in the Federal Reserve's discount rate, to 10 1/2 percent from 11 percent, was the third half-point cut in six weeks, and resulted in the lowest charge in nearly two years. ''The Fed is setting a clear policy of being more accomodative and injecting more reserves into the economy,'' said Producer prices for finished goods rose six-tenths of 1 percent, while industrial output and factory utilization fell slightly in July. Page 35.

The Occidental Petroleum Company yesterday offered to pay approximately $4 billion for the Cities Service Company, which has been scrambling to find a merger partner since the Gulf Oil Corporation withdrew its offer a week ago. Analysts and stock market traders expressed delight, saying the deal may save Wall Street investors hundreds of millions of dollars they feared they had lost when Gulf bowed out of its planned merger with Cities Service. In addition, experts suggested that the psychological impact of the multibillion dollar deal could buoy the entire stock market. Arbitragers Jubilant ''It's Christmas come early,'' said Michael Sofia, vice president of arbitrage at the brokerage firm of E.F. Hutton. ''Investors may look more favorably on stocks in general because of this,'' added William LeFevre, a market strategist for Purcell, Graham & Company.

Describing a tense and angry week of deliberations marked by confusion, four of the jurors in the Queens trial for the killing of one police officer and the wounding of another now say they are dissatisfied with their verdict, which one of them termed ''crazy.'' In seven days of deliberation, the jury was unable to reach a verdict on the major charge of murder in the death of Officer John Scarangella, but it convicted the two defendants on the lesser charge of attempted second-degree murder in the wounding of his partner, Officer Richard Rainey. The officers were sitting in the front seat of their patrol car on April 16, 1981, in St. Albans, Queens, when two assailants fired more than 30 shots into the car. Of the 12 jurors, only five agreed to be interviewed about their deliberations. The others either could not be reached or declined to talk about the case.

Israel's Defense Minister said he would accept a decision restricting military action in Beirut. Page 5. BEIRUT, Lebanon, Aug. 13 - Negotiations on withdrawing the Palestine Liberation Organization from west Beirut resumed today. The P.L.O. leadership sent the special United States envoy, Philip C. Habib, a list of the guerrillas to be pulled out and the Arab countries willing to accept them.

A march by thousands of Solidarity supporters in Gdansk was broken up by the riot police outside Communist Party headquarters today, and gatherings to mark eight months of martial law were dispersed by the police in three other major cities. The demonstrations and clashes were the largest outbreak of street protests since nationwide rioting on May 3, but the level of violence reported in Gdansk, Warsaw, Cracow and Wroclaw was considerably lower than then. Despite reports of heavy police force, there were no immediate reports of casualties. The actions marked the first of several major anniversaries this month when protest demonstrations are posible, and the police reaction indicated that the authorities intend to deal forcefully with any attempts at mass action.

The Manoir Bar sits on the floor of a valley that was gouged out by a meteor millenia ago. Until two months ago the men drinking in the Manoir worked for two large companies and earned some of the highest industrial salaries in Canada digging and processing the ore churned up by that meteor. Now, over beers, they tried to explain to themselves and to a visitor how this recently prosperous city had become the place with the highest unemployment in Canada, in the northern hemisphere and, some said, in the industrialized world. Last month the two giant nickel and copper companies around which this city of 135,000 grew, shut down operations and furloughed their workers because their stockpiled supplies far exceeded the demands of industrial users in the United States and Europe.

The Greenpeace environmental organization said today that it had halted an effort to prevent a British ship from dumping nuclear waste in the Atlantic. Six Greenpeace members who had chained themselves to the British ship Gem returned to their own vessel, the Sirius, which was on its way to the French port of Brest, the group said. The Gem, chartered by the British Atomic Energy Authority, began dropping its cargo of 2,700 metric tons of low-level nuclear waste on Monday about 400 miles off northwestern Spain.

The North Atlantic Treaty Organization announced today the appointment of Adm.

AROUND THE WORLD; Indian Opposition Irked at Mrs. Gandhi NEW DELHI, Aug. 13 (Reuters) - Indian opposition parties walked out of Parliament today accusing Prime Minister Indira Gandhi of disrespect because she did not make a personal report on her recent visit to the United States.

President Teodoro Obiang Nguema of Equatorial Guinea will remain in power for the next seven years under a proposed constitution to be put to a referendum Sunday, diplomatic sources said here today. They said President Obiang, a colonel, was elected to the sevenyear term by the West African country's governing Supreme Military Council on Aug. 2, the third anniversary of the military coup he led against his uncle, President Nguema Biyoto Masie, who was executed. The constitution provides for the military council to give up its governing role and for a legislative assembly to be elected by universal suffrage.