President Reagan understands that runaway health-care costs threaten to reduce the availability of health care available to the American people, and so he supports the notion of "cost containment" for health care.

But when it comes to the Pentagon budget, the president seems convinced that more spending automatically means better defense. Just last Friday, he was telling the National Association of Manufacturers that a House-passed "cost containment" plan to freeze military spending at present levels would "put the defense of our nation at risk."

Well, at least as good an argument can be made that the military spending the president wants ultimately will result in less military strength. J. Richard Munro, president and chief executive officer of Time, Inc., has been making precisely that argument. America, officially at peace for a decade now, is spending defense dollars as though on a wartime footing, Munro said in a speech last month at the University of Richmond.

"Defense spending in constant dollars now is as high as it was at the height of the Korean War and the Vietnam war," Munro said. "By 1990 it will be a third more than it was in either war. . . . In short, under the current leadership, we have the equivalent of a wartime spending policy. Our economy is being increasingly militarized." The paradoxical result, he said, will be "ultimately less military strength than we have now."

And how will that happen? "The defense buildup is taking place as if it were in a vacuum and had nothing to do with the rest of our economic and social needs," Munro said. "Yet it can -- and will -- cause severe economic dislocations affecting every industry in America. The shift toward more military spending in the 1980s will change our economy as deeply as the oil price explosion changed us in the 1970s. We have severely cut education and human services programs, and state governments are following suit. In effect, we are disinvesting in people, disinvesting in our future work force.

"Where will the skilled workers come from to help us fulfill the optimistic administration forecasts for future prosperity. They don't just walk out of the woods and into the front doors of our offices and factories. They come up through our system of schools and colleges. They receive nutrition and health care that keeps their bodies whole. Their families receive aid to keep them housed and clothed. They get help -- these are not just poor kids, either -- at every step by public spending programs which have in the last half-century helped create the world's most productive work force."

Munro sees clearly what too many of us fail to see at all: that the combination of budget slashing for domestic programs and increased spending by the Pentagon is distorting our economy in ways that will not strengthen the country but only weaken it. This is no argument against a strong defense -- still a vital necessity in this unsettled world. It is only a reminder that what President Eisenhower said 25 years ago is still true: "There is no safety in arms alone."

The paranoid householder who spends the food money, the school money, the health money and the clothing money on the very latest in weapons, steel bars and burglar alarms does not make his family more secure. Nor is America more secure when, in the name of peacetime national defense, we allow the Pentagon to consume our education, our industry, our capital and our supplies of skilled labor.