IDEALLY, PRESIDENT CARTER already would have enunciated a comprehensive and comprehensible policy toward the world's poorest nations, for which he expressed a special sympathy during the campaign. But he hasn't gotten around to it yet, and when he does, he'll find it's a tough job. The North-South problem, as it's called, doesn't lend itself easily to political packaging and executive-branch management, as do such matters as Soviet-American relations or the Middle East.It's messy, the economics of it are enormously complex, and Congress imposes sharp restraints on policy. President Carter, in his public appearances and even in some of his private ones, has made the right noises. But he has not organized the administration follow-through that alone would help some of the more controversial North-South issues along on the Hill.STSo it is that the United States now faces a serious political embarrassment in respect to the international lending agencies that, the administration says, constitue the centerpiece of its approach to the poorest nations. A multi-year contribution had been pledged to the International Development Assoication, the soft-loan branch of the World Bank, serving the most vulnerable countries. But the authorization is ensnarled in a debate over whether the aid should be tied tightly to American human rights issues(the Harkin amendment) or whether the executive should be allowed some discretion in supporting particular loans(the Reuss amendment). Not suprisingly, conservatives support the ultra-liberal position, seeing in its demands for high performance-demands that they doubt can be met - a way to kill foreign aid. Our own preference is plain: dogma, even the dogma of virtue, is not always a friend to development. There may be egregious exceptions, but, in the main, the United States cannot claim an unrestricted right to reform and transform other societies. In the long run, development-by reducing the need for represion as a method of containing popular frustration-may offer the best assurance that human rights standards will be observed.

Separately, the House has arbitrarily pruned back funds pledged to the Inter-American Development Bank, the largest and best run of the regional lending agencies. The Senate is due to try to restore some of the appropriation today but the House's cut was such that the result cannot fail to leave the United States in serious default. The Latins, whose support for the bank is conditioned formally and politicallyon that of Washington, will almost certainly suspend part of their own pledges. A major instrument of inter-American cooperation has thus been needlessly weakened.

An administration that prides itself on its quick start in other foreign-policy areas has been remiss in pulling together a policy on the North-South issue. Meanwhile, events keep crowding in, committing the administration to stances that limit the choices it can explore. Mr. Carter must find early occasion to set forth a North-South strategy that will give his administration a chance to shape events, rather than to be pushed and shoved by them.