Navy secretary John F. Lehman Jr. has correctly perceived that there may be lessons for American defense planning in the naval encounters near the Falkland Islands. It is worth remembering that there has been no significant example of war at sea since the early 1940s. While weapon capabilities have changed enormously since then, military planners have had to rely upon simulation exercises and lessons of the distant past.

It's necessary, of course, to resist the temptation to read too much into the Falkland experience. The conditions of battle are unusual and the details of what happened are still obscure. But the seeming ease with which the British dispatched an Argentine cruiser--and the Argentines responded by sinking a British destroyer--was certainly a powerful reminder of the vulnerability of large surface ships in the age of increasingly accurate antiship missiles and torpedoes.

Secretary Lehman, however, draws a different conclusion from the exchange. The British warship was vulnerable, he argues, because it was not afforded the protection of a modern carrier task force. His service is seeking to add two additional big carriers to the Navy's current fleet of 13. A fully equipped carrier task force projects a formidable amount ot power. But such a task force costs upwards of $12 billion to build. The survivability of big carriers in an all-out battle is much in controversy. Their offensive utility is limited in some measure by the fact that a carrier's planes and supporting ships must be devoted to protecting the carrier as well as to projecting power.

The carrier dispute should not be settled, however, within the narrow context of whether the Navy might better spend its additional money on other kinds of carriers or other ships. Military services tend to plan on the basis of weapons with which they are familiar and to match an enemy buildup in kind. There are cases, however, in which the best response to a new threat to one service's weapons may be increasing the role of another service--for example, using Air Force long-range bombers to attack an enemy fleet. New technology or tactics may also help overcome an enemy's existing advantage

These are the sorts of issues that need the careful consideration of civilian and military policy-makers as the nation begins the largest peacetime defense increase in its history. If there is one benefit from the fighting in the Falklands, it may be to sharpen this discussion.