THE Chinese massacres underscore the timeliness of a new book, The Democratic Imperative (New Republic/Basic Books). How do we effectively encourage democracy in the authoritarian and totalitarian regimes? Author Gregory Fossedal, a research fellow at the Hoover Institution and syndicated columnist, has a simple thesis: U.S. foreign policy has been too reticent in promoting democracy. "Most politicians would willingly admit to the universality of the rights in our Declaration of Independence; yet they steadily refuse to acknowledge that our foreign policy should be based on them."

He advocates placing "greater emphasis on public diplomacy, on explaining and strengthening the democratic idea throughout the world, [through strengthening] such levers of influence as the Voice of America, Radio Free Europe/Radio Liberty and other means of reaching people of other countries." Thus, VOA should have facilities to broadcast to China 24 hours a day instead of the usual 11, facilities strong enough to overcome jamming. Ideas are potent. This plus judicious sanctions may well prod Beijing to a reform path again after the current frenzy of bloody repression.

Fossedal takes a refreshing look at the use of tools such as economic sanctions, international law, foreign aid, international broadcasting and the arming of guerrilla forces in other countries.

The Democratic Imperative's best chapters are on the failures of Jimmy Carter in Nicaragua and Iran. The U.S.' distaste for Somoza and the Shah was not misplaced, Fossedal believes. Our big mistake was that, after encouraging removal of these authoritarian figures, the U.S. in effect took a powder, doing little to help the democratic forces in those two countries, which were stronger than recognized. In short, we left our pro-democracy friends dangling. Communism in Nicaragua and religious fanaticism in Iran were not inevitable outcomes.

The author is also right in his hard criticisms of the International Monetary Fund, which has been a destabilizing force in Third World economics.

The book has flaws, as numerous critics have pointed out. The author seems to ignore, or to be too impatient with, the constraints of the real world, an attitude that cost Woodrow Wilson ("making the world safe for democracy") dearly after World War 1. Fossedal takes too benign a view of the communist-dominated African National Congress in South Africa. His idea of a League of Democracies isn't convincing.

It would perhaps be too much to say that these shortcomings are beside the point, but they shouldn't blind us to the correctness of the book's basic thesis. Democracy in a great power is not incompatible with an effective, active foreign policy. Used correctly, in fact, it is a most formidable tool.