THERE ISN'T muct sense in deriding President Reagan just to score political points. Given half a chance, or one positive White House policy initiative, most liberals would happily applaud the president. But over the past two and one half years, no such initiative has appeared. And this week, just when it seemed that opportunity for bipartisan approval of the Administration had finally developed, Reagan botched it and invited another dose of rightful scorn from liberal quarters.

In the wake of Philippine opposition leader Benigno Aquino's murder, pressure had mounted on Reagan to cancel his visit to Manila scheduled for November. The trip, it was argued, could be seen only as a gesture of support for the brutal Marcos regime and tacit absolution for Marcos and his cronies for their likely involvement in the Aquino slaying. When Reagan actually decided on Monday to forego his Manila jaunt, there was some short-lived rejoicing within the anti-Marcos camp both here and in the Philippines. Reagan, it seemed, had seen the light of reason on at least one issue.

But it didn't take long for Reagan to erase his one positive policy step with a much larger stride in the opposite direction. Instead of coming right out and admitting his qualms about the Marcos regime, the President gave the most namby-pamby excuse heard in recent months to explain the cancellation of his trip. In what amounted to a letter of apology to Marcos, Reagan assured the Filipino President that he would have gone ahead with the visit if it were not for a "problem with Congress." Adding more verbal saliva to Marcos' bootstraps, Reagan wrote that he was looking forward to meeting with Marcos "when a mutually acceptable date can be set" and that "our friendship for you remains as warm as ever."

For his part, crafty Marcos played the game just right. In a written response to Reagan, he attributed the President's change in plans to concern in Washington about the latter's security. In other words, Marcos was claiming, the ongoing opposition demonstrations and the climate of violence they have entailed derailed the Reagan trip--not the repression that characterizes the regime itself. And Marcos had the hypocritical gall to mention in his letter the "traumatic experience" of Nancy Reagan after her husband was wounded two years ago in an assassination attempt. No doubt Mrs. Aquino appreciates the irony of that line.

SOME foreign policy "pragmatists" would argue that Reagan already compromised U.S. interests in the Philippines by cancelling his trip. Coating the decision with soothing language, they would say, merely makes it an easier pill for Marcos to swallow; given the existence of two key U.S. military bases on the Philippines and Marcos' unflinching support for Washington, maintaining the status quo is a valid priority. And besides, they would add as an afterthought, echoing Machiavelli and Tallyrand, morality has no place in U.S. policy. The president does what has to be done for reasons of state.

Even granting for a moment the last point, the "pragmatists" are wrong. This Administration's policy toward the Philippines runs counter to our interests. In the long run, it will prove disastrous.

Propping up Marcos will only serve to polarize the political scene in Manila. The Filipino center symbolized by Aquino is still a vibrant force, capable of assuming leadership and reinstating democracy. But if Washington continues to ignore the center in favor of Marcos, increasingly frustrated centrists will move to the extreme left. Then the Communists will constitute the only viable alternative to Marcos. And unless the latter dismantles the authoritarian state apparatus he himself erected--an unlikely prospect--the Communists will take power and the U.S. will be out in the cold. No moral argument here, just sheer pragmatism.

Of course, supporting the center would be the most intelligent policy option from this country's perspective. And it would just happen to be the most moral course we can adopt as well. So morality and foreign policy can coexist--if not always, at least sometimes. But as evidenced by Reagan's latest blunder, the policymakers in Washington don't see the light. Instead, they are leading us down a familiar path, one already followed in El Salvador and Nicaragua.

In the Philippines, though, our options are still open to some extent. It's not too late to reverse course and opt for the road not taken.