THE WHITE HOUSE would be wise not to spend a great deal more time pondering whether to reappoint Paul Volcker at the Federal Reserve Board. President Reagan's careful silence on the subject, and the reports of divisions among his staff, inevitably create the impression that Mr. Volcker is a lame duck. Interest rates have been inching uneasily upward for several weeks, reflecting the deepening uncertainty in the financial markets. If Mr. Reagan really intends to replace Mr. Volcker, then--like the murder of Duncan, king of Scotland--it were well it were done quickly.

But it were better if it weren't done at all. As chairman of the Federal Reserve, Mr. Volcker has served with great skill and courage through four very difficult years. On the hard questions he has been consistently right. If the quality of the performance were the only criterion, he would deserve reappointment.

But Mr. Reagan is said to have wanted someone out of his own camp, a new face, perhaps--a slightly less creditable thought--a figure not quite so closely associated with the painful experiences of the past several years. It would be difficult to argue that, out of 235 million Americans, there is no one else who could possibly do the job. The debate within the White House has reportedly come down to a choice between Mr. Volcker and the economist Alan Greenspan. That's a good sign, for Mr. Greenspan is the best qualified, by a wide margin, of all the possible candidates whose names have been floated over the past months. By every indication he would follow a policy very similar to Mr. Volcker's.

But the president needs to give special care to the question of technical expertise. The most imminent threat to economic stability, not only in this country but around the world, is the gigantic accumulation of international debt. The debtor countries can't pay their creditors unless there is a sustained recovery of world trade. But any major default would result in, at the least, a prolongation of the recession. To work out of this peril will require time, steady nerves and much careful work by finance ministries and central banks throughout the world. The leadership will have to come from the United States, and in the United States government competence in international finance is now mainly centered in the Federal Reserve Board. There is no one who matches Mr. Volcker in both political standing and grasp of the intricate networks that make up the world's financial system.