`Theirs not to reason why...'

IN thinking over the drama of Lt. Col. Oliver North's appearance before the congressional committee investigating the Iran-contra affair, it is prudent to remember that the valor of the soldier does not measure the worthiness of the cause in which he displays his valor. Colonel North is the epitome of a fine soldier.

He is not only valiant and dutiful. He is also zealous and imaginative in the performance of the work assigned to him. No commanding officer could ask for a better subordinate to lead men into battle or to conduct a secret operation.

It is a prime characteristic of such men in all armies in all times that they accept implicitly the worthiness of the cause for which they are working. North never doubted the worthiness of the work assigned to him at the White House. He became not only a diligent and devoted executor of White House wishes. He became the most persuasive propagandist yet for the cause of supporting the contras in Central America.

Great armies are made up of just such fine young officers. The classic tribute to such men, and also the classic characterization of them, was written by Alfred Lord Tennyson. ``Forward, the Light Brigade!'' Was there a man dismayed? Not though the soldier knew

Someone had blundered. Theirs not to make reply, Theirs not to reason why, Theirs but to do and die.

Lt. Col. Oliver North is not a student of political science. He is not a historian. He is not an elected politician. North is not an appointed policymaker in the government in Washington. He has no credentials for having an informed opinion on the merit of the policies that are under investigation by the committee.

The information to be found in his personal story is of crucial value to the committee in search of what happened, how it happened, and who was responsible for the happening. But his opinion on the merits of the policies is irrelevant. North is an admirable soldier. But there remains the question of a policy that attempted deliberately to ``circumvent'' the explicit decision of the Congress.

And there also remains the question of ultimate responsibility for that attempt to circumvent the decision of the Congress.

The important thing about North's testimony is his obviously sincere conviction that everything he did had been authorized by his superior officer, Vice-Adm. John Poindexter. There is a side question here as to whether Admiral Poindexter was entirely aware of a special relationship that apparently existed between North and the director of the Central Intelligence Agency, William Casey.

Was North working at the same time for both the President's official adviser on national security, Poindexter, and the head of the CIA, Mr. Casey? Were Poindexter and Casey collaborating? Were Poindexter and Casey consciously trying to do what the President presumably wanted done, but without telling the President about it?

There are plenty of exciting angles of the story still to be cleared up. And in the end will Congress continue the contra policy or end it once and for all? Finally, there is the old and unresolved question of the extent to which any president can conduct foreign policy without the support or at least consent of the Congress. The Reagan White house is currently contending that it has a constitutional right to do so. Experience indicates that as a practical matter the President had better be sure he has a majority in the Congress behind him before he undertakes a controversial foreign policy operation.

It is argued that Lincoln, Wilson, and Franklin Roosevelt all did illegal things. True, but they were careful to have potential majority support in the Congress first. None acted illegally against a prior negative majority vote.