Major league baseball umpires went back to work Saturday but may soon strike again. The umpires were working under a contract that was supposed to be binding upon both sides through 1981, but labor contracts are mere scraps of paper these days.

CIA agents who accept as a condition of employment the restriction that they will not reveal agency secrets write books that reveal agency secrets. Postal workers who accept as a condition of employment the restriction that they are prohibited from striking, strike anyhow. Policemen, firemen, garbage collectors, Metro workers and other public service employes barred from striking (by law or by contract) also strike at will. So why can't men who get four months of vacation every year breach their contract and demand extra extra vacations during the height of their busy season?

What's worse, it is now standard procedure for each contract wrangle to escalate into all-out economic warfare. Quite often neither side bargains in good faith. Both seem eager to begin the head-knocking and teach the other side a lesson.

In the 38th day of its strike against the Norfolk and Western Railway, the Brotherhood of Railway and Airline Clerks charged that the railroad had been receiving $800,000 a day in "mutual aid" payments from other railroads. As a result, said the union's president, Fred Kroll, the N&W "has no inducement to sit down and conduct meaningful negotiations" with the union. In the 46th day of the strike (Friday), the company went into court to ask for an injunction against union interference with the railroad's attempts to continue service.

The chief issues in the N&W strike were stated to be "working conditions and rules." In the strikes against New York's newspapers, the terms are "manning" and "work rules." These are all code works for the same basic issue: Does management have the right to determine how many people it needs, or will the number of employes hired be dictated by unions? In short, they're fighting about featherbedding.

Management argues that it must be free to use new technology to reduce its work force, by attrition if not by layoffs. Unions argue that an employe has a right to resist being replaced by a machine, and a union has a right to resist a reduction in the number of jobs under its jurisdiction.

There is no need to debate that disagreement here because by this time almost everybody has made up his mind about it. What does need to be looked at is Fred Kroll's complaint that the N&W isn't inclined to bargain in good faith because it is collecting "mutual aid" strike insurance.

Mutual aid is as basic to union strategy as to management's. In the 19th century, employers had the economic power to work their will. Employes learned that as individuals they were weak. They could match management's economic power only if they banded together.

Workers learned to call each other "brother" and "sister," and to contribute to strike funds that paid benefits to brothers and sisters on strike. Unionized workers also learned that boycotts could be effective. A union man didn't cross another union man's picket line, regardless of the merit or lack of merit in the striker's position.

The essense of this approach is that a contract dispute is an economic war, and in war one must mass his forces and employ them against the enemy in any way that seems likely to achieve victory. Owners and managers, some of them distressingly dimwitted in the area of human relations, were bright enough to recognize that, for them, too, unity would bring strength. Their choice was simple: either organize their own ranks into more effective battalions or face defeat.

So both sides became stronger, and today both have the means to escalate localized labor disputes into massive collisions between huge and powerful associations. Neither has any great inducement to "sit down and conduct meaningful negotiations" because both have been paying into strike insurance funds for years - in effect, stocking their arsenals with the basic weapons of economic warfare: unity and money. Now they're just itching to have at each other. "Lay on, Macduff, and damn'd be him that first cries, 'Hold, enough.'"

The question is no longer whether there may be a better way to handle labor disputes. The question has now become: Is there a worse course than permitting unrestricted economic warfare to determine the terms of contract settlements?