THE JAMAICAN election returns are a resounding repudiation of Prime Minister Michael Manley's march toward socialism. The conventional wisdom holds that economic decline pushes voters to the left. But after nearly a decade of steady erosion in their standards of living, Jamaica's voters have new swung to the center-right to bring Edward Seaga and his Jamaica Labor Party to power.

As the returns came in, Mr. Manley bitterly declared that his defeat was the penalty for challenging the power of the Western economic structure." He holds that the United States and the International Monetary Fund deliberately strangled the Jamaican economy to punish its leftist politics and, especially, its warm relations with Cuba. He succeeded in making Jamaica a symbol of every small country struggling to make its own way.

But he evidently failed to persuade most of Jamaica's voters that the accusation was accurate. It's a fair summary of the Jamaican case to say that, if a country organizes its economy to achieve high growth through foreign investment and trade, it cannot safely indulge in the kind of political gestures that threaten investors and traders. Mr. Manley's style and rhetoric aggravated the capital fight of the mid-1970s. The government then tried to compensate by borrowing. By the time it finally turned to the IMF, it had built up huge payrolls and budget deficits that it was unable to control. The deficits eventually violated the IMF's lending conditions, and even that source closed up. Since last spring, trade has stagnated and traders have had to turn to the black market for foreign exchange. Meanwhile, squads of armed men on both sides of the election campaign have been engaged in a sinister and bloody kind of guerrilla warfare through the streets.

The incoming Seaga government will certainly turn to the IMF, which will equally certainly resume lending to Jamaica. The IMF has never before found itself an ideological target in this degree, and it is anxious to reopen relations with Jamaica. That will provide foreign exchange. But attracting investment will be harder. Investors don't put much money into a country where they fear continued turmoil and street fighting.

Mr. Manley, in defeat, is entitled to great credit for his fidelity to the principle of democracy. He said repeatedly that he would submit his program to the voters, and he kept that promise. He now has a further responsibility. The present level of political violence will continue until the parties' leaders intervene, with fortitude and determination, to stop it.

Jamaica is not an impoverished land. If the world's countries are ranked by wealth, it is in the middle, in the same range as Mexico and Korea -- with richer natural resources than Korea's and a better educated population than Mexico's. There are promising prospects for growth. Some of the financing for it can come from outside Jamaica. But only Jamaicans can provide the other necessities -- social stability and civil peace.