Picking on China -- a new fashion

China accounts for a quarter of mankind. America accounts for a quarter of the world's gross product. Their combined weight is overwhelming and can serve as the most positive single factor in world affairs. To lump the two countries together is not sheer fantasy. There is a solid basis for cooperation.

China and America have overriding common interests - and not just in terms of strategy. What is more, in spite of the immense differences in culture, social system, and ideology, there is an unmistakable, if inexplicable, temperamental affinity between the Chinese and American people. Indeed we sometimes become infatuated with each other.

All this is no mystery, and is appreciated by most unbiased Americans. There would have been no need to belabor the point had it not been for the recent spate of media reports that paint a grim picture of the People's Republic. It is amazing how far China's critics are willing to go. Harper's says China ''stinks.'' William Buckley calls the Chinese system ''odious and repressive.'' Congressman John LeBoutillier, on the authority of Alexander Solzhenitsyn, asserts the Chinese are worse than the Russians under Stalin. And the New York Times's Fox Butterfield describes China as a sinister police state.

As the value schemata are fundamentally different, the debate will go on indefinitely. But certain basic facts are beyond controversy. Compared with the rest of the third world, China has not done so badly. A billion people are adequately fed and clothed in spite of the fact that China has only 7 percent of the world's arable land. Widespread famine resulting from flood or drought plus misrule is a thing of the past. There is a rudimentary but effective system of health care. Life expectancy has nearly doubled. Those who sneer at China's backwardness should be reminded that China is one of a few countries that have orbited and recovered earth satellites and synthesized insulin.

It is true the state of affairs in China still leaves much to be desired. When the industrialized countries were making rapid progress during the late '50 s and the '60s, China was its own worst enemy. I am, of course, referring to the ill-fated Big Leap Forward and the catastrophic Cultural Revolution. And power has corrupted not a few.

But why this flood of criticism at a time when the present leadership is doing everything to correct past mistakes? What are China's critics up to? Are they calling for a US (Western) crusade against China as well as the Soviet Union? (They are already pushing China toward the Soviet Union.) Have they lost all sense of reality?

It would be interesting to try to locate the source of this curious phenomenon.

A theory of conspiracy has been offered to explain this outpouring of venom. It is well-known that the CIA enlists the services of certain journalists and has a clandestine book-publishing operation. The Taiwan lobby is doing its best to poison the atmosphere. But the American system seems to operate too openly for conspiracies of such magnitude. Picking on China simply has become fashionable.

But the real culprit is ideology - anticommunism of a particularly intolerant kind. Unlike the British, who since Palmerston recognize no permanent friend or permament enemy, only permanent interests, Americans are moralistic. They are out to save souls, to preserve freedom and democracy, and to deliver the world from communism. Ironically, they often end up supporting military juntas and reactionaries of various stripes. There is even a ''theory'' to justify this. Authoritarian regimes, it is argued, are better than dictatorships because they can be democraticized peacefully. The favorite examples cited are Portugal, Spain, and Greece.

There are people who see socialist (communist) countries as immutable and thereby forfeit whatever levers there are that might be used to influence developments. But, of course, nothing in the world is unchangeable. Both the United States and China are changing. Ideology is admittedly very much alive in both. But they have to operate under increasingly stringent constraints. They may have to set ideology aside for modernization, or simply to overcome the severe recession.

When Seymour Martin Lipset and other Western thinkers saw the ''end of ideology,'' they were talking about the West alone, and in the sense that serious conflicts among liberals, conservatives, and even democratic socialists had declined sharply.

As for the world at large, especially as regards the third world, they claim, ideology (and passion) are still needed. I am not so sure about that. After all, we all live on a shrinking planet and share many common problems. Compared to preserving mankind from nuclear annihi-lation, ideology is pale and lifeless. We would do well to set it aside and get down to more urgent business.