It was always possible, as President Marcos maintained, that a hit man in communist hire had killed Mr. Marcos' leading political rival, Benigno Aquino Jr., in 1983. Although Mr. Marcos would never acknowledge it, there was a plausible motive: to diminish the middle ground in the Philippines and assure his continuance in power, since nothing serves the prospect of a communist takeover more. But no evidence was produced to tie communists to the assassination. On the contrary, a five-man civilian inquiry found that the military had planned, executed and covered it up. What counts, nonetheless, is that a court of three judges appointed by President Marcos has now acquitted his cousin, confidant and former bodyguard, Gen. Fabian Ver, and 25 others charged in the crime. Mr. Marcos promptly reinstated Gen. Ver as chief of staff.

The Marcos strategy is plain enough. His pliant judiciary has removed a potent threat to the institutional authority of the armed forces, his chief bulwark in power. A weak and manipulable political process that he utterly dominates should allow him to win handily the presidential elections he has scheduled for next February. With a few "reforms" to make the army a fitter force against the guerrillas, he will be able to tell the United States that the situation is improving and that any slackening of American support plays into communist hands.

This is, of course, farcical. The triumphs Mr. Marcos claims are counterfeit. By most testimony, the communist insurgency is gaining, and he has no effective program to counter it. Yet President Marcos is not without resources. He is shrewd, and he knows how to use the latent anti-Americanism that lies increasingly close, it seems, to the surface of the people's feelings about their erstwhile colonial master. The passion for freedom now expressed by his legal opposition has to be set against the membership of its prominent members in the same privileged class from which Mr. Marcos draws his cronies.

Here, it seems to us, is the heart of the matter. The opposition is falling down. It keeps sending out plaintive appeals for the United States to lean on the Marcos family, muscle it aside, cut aid, wink at a coup -- almost anything. It is distressed to find that the administration is reluctant to seem an unreliable friend and that it fears to start something it might not be able to contain. Meanwhile, however, the opposition resists the administration's quiet but earnest and worthy appeals for it to unite. Within the opposition there is no towering leader and little evident inclination to patch things up for the common good. It squabbles on, assuring Mr. Marcos an easy electoral ride.

And that in turn all but ensures the eventual success of the violent insurgency. Why does the democratic opposition not seem either to understand this or to care about it enough to act? What the United States could lose, if this awful likelihood comes about, is trivial compared with what they could lose. Increasingly, it seems, the tragedy of the Philippines lies in the undisciplined and indulgent performance of the only people who could save the place.