THE "BUSINESS LUNCH," as we Americans have known it for so many years, may be a thing of the past. President Carter, who doesn't drink, has always railed against people being able to deduct a "three martini lunch" on their taxes. Congressmen and senators, many of whom have ben recipients of the "three martini lunch," have offered a compromise proposal in the nex tax bill, which would allow only 50 per cent of a business meal to be considered deductible. The other 50 per cent would have to come out of the person's pocket.

The fight against the expense account business lunch has always been a very popular issue with the masses.

But let me, for the moment, be devil's advocate and point out that the business lunch is essential to a healthy American economy. Most big deals are made at a business lunch involving not only money but orders for goods, which means jobs for millions of people.

Let's say Mr. Jay wants to sell Ms. Zee 3,000 dresses for her department store. Mr. Jay takes Ms. Zee to a beautiful French restaurant in New York and buys her a delicious meal with the finest wines. Ms. Zee feels very, very good and orders Mr. Jay's whole new line. Mr. Jay goes back to his office and tells the factories to start humming. He deducts the paltry $80 lunch, but the government gets hundreds of thousands of dollars in return in the form of taxes from Jay's employees.

Under the new tax plan, Mr. Jay may take Ms. Zee to an inferior Chinese restaurant, order a half pot of tea and insist on splitting his sweet and sour pork with Ms. Zee.

Ms. Zee thinks to herself, "If this guy is so cheap at lunch, his clothes must be cheap too. I'm not going to buy any of them." Mr. Jay calls the factory and tells them to shut down. For a lousy $40 that Jay couldn't deduct for a decent lunch 500 people are put out of work.

All right, if you don't like that example, what about this one?

Parsons is trying to sell the Pentagon a new antihand grenade. His firm has strict orders that he cannot spend more than $20 for lunch. He takes Gen. Cain, the Pentagon procurement officer, to a five-star Italian restaurant. They order three martinis each. Parsons has blown the entire $20. Gen. Cain says, "Let's order." Parsons says, "I didn't invite you for lunch. I invited you for drinks."

Gen. Cain says, "Well, if that's the way you feel about it the Army doesn't want any of your antihand grenades."

"Then," Parsons says angrily, "You can pay for your own dry martinis."

For a lousy filet mignon the tax reformers could drive an irreparable breach between the military-industrial complex.

Maybe you don't like that example. Let me try one more.

Burt Arrow, head of one of Atlanta's largest banks, is trying to get the account of one of the biggest paper mills in the state. He invites the chairman of the board, Billy Joe Sherman, to lunch.

"Where shall we eat?" Billy Joe says.

"How about the University of Georgia football game at halftime? I'll fly up in the bank's private plane," Burt says.

The two men meet at the hot dog stand during the halftime show. They order two hotdogs and two bottles of Coca Cola. Burt talks to Billy Joe about moving his company's account over to Burt's bank. Billy Joe says he'll think about it.

Burt pays for the hot dogs and Coca Cola and writes them off on his income tax, together with the plane ride. The IRS claims Burt can only write off Billy Joe's hot dog and Coca Cola.

Burt hires Clark Clifford to defend him. The ensuing publicity drives Burt's bank stock down three points, and Billy Joe decides to keep his money where it is.

It's obvious from these three examples that doing away with 50 per cent of the tax-deductible lunch is counterproductive.

Having a meal on the expense account is what the American dream is all about. Everbody should be for it and say, "Even if I can't have a complete tax-deductible lunch, some day, God willing, my children can."