For strictly on the merits, there is only a raggedy case to keep buying more F-22s.
The F-22 was developed in the 1980s as one of several aircraft—the B-2 bomber and F-117 attack plane were others—to incorporate "stealth" technology: flat, rounded surfaces and special materials that together made the plane all but invisible to radar.
The F-117 saw action in the 1991 Gulf War and in Kosovo, but its stealthiness played only a limited, if important, role. In Kosovo, Serbian air-defense crews shot down one F-117 after calibrating their radar systems to peer through the plane's "stealth features."*
The B-2 was originally designed as a nuclear bomber—a stealthy follow-on to the B-1—but the Cold War was over by the time it entered the fleet, so it has spent most of its combat hours dropping conventional "smart bombs" from altitudes too high to be reached by anti-air defenses in any case.
One lesson learned from the wars of the last two decades is that U.S. combat planes are very hard to shoot down, whether they have stealth technology or not. This is due in part to the radar gear in even the older planes, in part to the tactical skills of the pilots, and in part to the mediocrity of our enemies.
But what if our planes keep getting older and our enemies get better? Even the F-22's advocates concede that there'd be no need for this aircraft if all our future foes were the likes of Afghanistan or Iraq. It's easy to control the skies—so that helicopters can strafe, planes can drop smart bombs, and our troops can roam the terrain without fear of attacks from the air—when the enemy has a lousy or nonexistent air force.
The main scenario justifying the F-22 is a war against China or a resurgent Russia. True, neither country has much of an air force now, but in a decade they might; and if war broke out under those conditions, "air superiority" would be much harder to achieve.
Some contend that we're in bad shape right now. In the "Cope India" air-combat exercises of 2004, American pilots in F-15Cs—the most sophisticated U.S. fighter plane of the day—went up against Indian pilots in much older French and Russian jets and lost 90 percent of the time. Air Force magazine reported on the results at the time and concluded that the F-15s were aging a lot more drastically than anyone had assumed and that we therefore needed the F-22s—and a lot of them—as quickly as possible.
Yet there were some red herrings in that war game. First, the Indian planes outnumbered ours by a ratio of 10-, or sometimes 12-, to-4. Second, since this was a training exercise for the Indians, the U.S. pilots were playing the "red team" and thus simulating the stiff tactics of India's enemies; they weren't pulling the maneuvers that they would routinely manage in their own exercises, much less in a real air duel.
Third, since the Cope India exercises, several F-15Cs—and also many of the Navy's carrier-based F-18s—have been fitted with new Active Electronically Scanned Array (AESA) radar systems, which allow the pilot to detect, track, and destroy several enemy planes at once from significantly longer ranges.