Human rights policy is still a primitive art. After more than three years of varying degrees of governmental activism out of Washington, few people have a clear notion either of what it was meant to achieve or the range of weapons available to make critical rhetoric stick.

President Carter in his speech at the Democratic convention turned to the subject with some passion. But he limited himself to a call for human rights in the Soviet Union and Eastern Europe -- the part of his policy that has been most criticized, not least by his West European allies, who feel that it has riled the Soviet leadership and gained little freedom for those persecuted.

Meanwhile, events in Bolivia and South Korea throw into relief the Third World side of the coin. Bolivia, a country the United States should be able to hold in the palm of its hand, appears, at least for the moment, able to withstand all pressure, including a wide range of sanctions, to honor its recent election. It has found refuge in Argentina's single-minded effort to outwit Washington, whether it be by grain sales to the Soviet Union, nuclear proliferation or human rights.

South Korea, for its part, knows that as long as there is a North Korea it can mock Washington's human rights lobby. Before the Soviet invasion of Afghanistan, Washington might have been prepared to take a few risks to push for change in South Korea. Now, however, it will do nothing that might be interpreted as a weakened military commitment.

Before Afghanistan there was a widespread feeling in Seoul that to repress and then be forced by outside pressure to loosen up would be destabilizing. The shah's Iran had demonstrated that truth. Today, the new military rulers, reasoning that Washington's order of priorities has changed, seem to feel that they can get away with repression, however ruthless. Washington, the ruling clique appears to surmise, will huff and puff, but it will not use any weapons that really hurt.

That raises the question of what weapons do give discomfort to the point of compelling change? Rhodesia, Iran and South Africa in particular have highlighted the complexities of sanctions.

For a decade or more, the world was mandated by United Nations Security Council resolutions to embargo all trade with Rhodesia. Rhodesia -- known since independence as Zimbabwe -- survived, aided by its immediate neighbor, South Africa. It also received substantial help from countries as varied as Japan, Australia, the United States and the Ivory Coast. Moreover, the British oil companies, flouting their own government's laws, provided oil in the quantities required. In the end, it was the guerrilla war that brought the whites to the negotiating table. Similarly, West European nations, India and Iran's neighbor, the Soviet Union, have run rings around the U.S. embargo of Iran.

South Africa, it is argued, could be different. If the West would agree to mandatory U.N. sanctions, no country would dare buck them. South Africa would have no nearby friends and its shipping lanes and air links could easily be patrolled. But would a total blockade actually bend white South Africa's will? Or would it merely make the country determinedly self-sufficient? No one has produced watertight argument either way. However, there is ample evidence to show that the sports boycotts have forced changes in South Africa's apartheid practices. This leads many South Africa-watchers to argue that what is needed is more selective boycotts, aimed at achieving specific goals, rather than all-encompassing embargoes.

Leaving these problems on one side to take a global view, it is remarkable how rapidly the world scene has changed since President Carter embarked on his human rights crusade.

Africa, which had only two functioning multiparty democracies in 1977, now has at least seven, including Nigeria, its most populous nation. The number of political prisoners has fallen dramatically.

In Asia, India has returned to constitutional rule. In China, despite the toing-and-froing over Democracy Wall, progress has been made toward more political liberalization. In South America, apart from Bolivia and Guyana, the northern countries appear to be firmly in the democratic camp. Brazil may join them in the not-too-distant future.

Can one thank Carter for this? Not in a direct way, since cause and effect often appear so far apart. Without doubt, however, the administration's constant, if not lately so loud, articulation of the issues has given the human rights ball a mighty shove. It has helped highlight the foot-slogging work over the years of Amnesty International, Freedom House, the International Commission of Jurists, the churches and the labor unions. Carter may not have single-handedly pushed any of the worst offenders into line.

Nevertheless, the constant refrain of human rights, and U.S. voting patterns at the United Nations and in other international institutions, helped provide a climate conducive to world political liberalization. On a number of important occasions, in particular with Zimbabwe and Nicaragua, the administration indicated the strength of its commitment by refusing to support halfway-house compromises that would have kept narrowly based oligarchies in power.

The canvas is still half-filled. The brush strokes are still fuzzy. Only when one steps back can one discern a shape. But it's a more democratic and less repressive world than it was.