China is an economic catastrophe waiting to happen. China is poised to become the world's largest economy by 2025. Both these statements are true. They provide the context we must understand in order to evaluate rightly what the Chinese are attempting to do in the sciences.

When Deng Xiaoping came to power in the early 1980s, China was a Third World country, its vast population mired in poverty, trapped by massive economic failures and structural rigidities. Deng decreed that China must have the benefits of capitalist modes of investment and competition. He declared, also, that the foundation of economic and so of national greatness is science and technology.

A quarter-century later, the dynamism of the Chinese economy is without precedent -- steel, automobiles, toys, textiles, household appliances, on and on. Official statistics put the year-on-year growth of gross domestic product at 7.5 percent in 2001, 8.3 percent in 2002, 9.3 percent in 2003, 9.5 percent in 2004. Some Western economists think the real rates have been significantly higher. In any case, agreement is general that China's economy will soon outstrip that of the United States.

Yet its problems are on the same colossal scale. China has 1.3 billion people, predicted to peak at 1.4 billion in 2025 -- and 900 million are still rural and extremely poor. Corruption is widespread in provincial governments, in state-owned industries, within the Communist Party. The banking system is reported close to collapse. Social discontent is erupting: the government has admitted to tens of thousands of protests a year.

Poverty is not confined to the countryside. In the main streets and glossy shopping malls of Beijing in summer, slim young women are stepping out in gauzy short dresses and frivolous shoes, but a block or two away are ancient alleyways -- in Beijing called hutong -- lined with low crumbling buildings, rows of minute cavelike shops open to the street with no lights lit, middle-aged and older men and women sitting idle, smoking, sullen on the stoops.

Pollution is pervasive, environmental degradation devastating. Smog in Beijing, Shanghai, and other cities reduces visibility most summer days to less than half a mile: when you drive along one of the elevated highways that cut through Shanghai, office and apartment towers emerge spectrally from the haze and then dissolve away. Seventy-five percent of China's lakes are said to be polluted; the lower reaches of major rivers run dry many days of the year.

The problem most publicized is energy. China is already second only to the United States in energy use. Domestic oil or natural-gas supplies are negligible. China has abundant coal, of which it is the largest global consumer, mining and burning a quarter of the world's yearly output -- at disastrous cost, some 6,000 miners killed underground in 2004 alone.

Even sophisticated and knowledgeable Westerners bring ideological preconceptions to their view of China. The most common is that economic growth requires laissez-faire capitalism, ideally on the Anglo-American model -- and will inevitably lead to democratic reforms. But Chinese capitalism is not like, and will not necessarily approach, the Western model. It is under state control -- often erratic, to be sure, yet always threatening. The steel industry, the automotive industry, and the others were created from the top down. Goals are still set from on high, in five-year plans, and in detail.

The men at the top are a new generation, intelligent, determined, relatively young. No question that they have learned from history -- but not the lessons Western observers would like them to learn. Hu Jintao is paramount leader. He and his colleagues have attacked what they call "neoliberalism," specifically, laissez-faire policies. They admit no correlation between economic growth and any flowering of democracy. What had looked like a gradual relaxation of controls over press and television reporting has been reversed, sharply and increasingly.