ON ONE LEVEL James Webb may have acted admirably in resigning as Navy secretary the other day, but at a deeper level he was wrong. His sense of honor served him better than his judgment. Mr. Webb said he was stepping aside because he couldn't in good conscience support the cuts the president has proposed in Navy spending plans nor continue to serve under Defense Secretary Frank Carlucci, who was instrumental in proposing them. That's fair enough; who can criticize a man for giving up high office for his principles? But the cuts that led Mr. Webb to his decision were a long way from the savaging of the Navy budget that he described.

Mr. Webb mourned, among other things, the fact that the new budget is a retreat from the goal of a 600-ship Navy. But that goal has always been of greater symbolic than substantive importance -- and just a little bit of a game. The Navy was moving to achieve it not just by building new ships but by delaying the retirement of old ones. To save money Mr. Carlucci went the other way this tight budget year and ordered some retirements sped up. That puts a 600-ship fleet over the horizon, but in the greater scheme of these things it is no great loss.

The driving force in the Navy buildup has been the decision to go to 15 carrier battle groups. These have been the real source of both cost and controversy. The cost is as much for the escort ships and planes each carrier requires as for the carriers themselves. The controversy is over the intended use of these groups to project American power toward foreign shores. Critics say this is a showy concept and that in wartime the Navy wouldn't want to go through with it because the carriers would be too exposed.

The protective Reagan-Carlucci budget, to the consternation of some serious critics both in and outside Congress, retains the 15 carrier groups as well as the other basic elements of the expanded Navy. The only whiff of retreat on the carriers was a decision to reduce by one the number of naval air wings -- each carrier has its own -- but there would be reserves to replace this wing in time of need. The Navy had to cut planned spending by $12 billion, but the other services had to cut roughly comparable amounts. Mr. Webb should have been more thankful than indignant.

The Navy if anything needs to cut back even more. It is still not clear that it will have enough money to man and operate all the ships it is building. This is not just a fiscal issue; it will drain the service as much as it will drain the Treasury. Mr. Webb, brushing such considerations aside, was less than graceful in resigning. He said, among other things, of the Pentagon under Mr. Carlucci, "This building needs to be led." Leadership is precisely what it needs and what Mr. Webb, in exiting so indignantly, has declined either to accept or to provide.