The ranch at Crawford hardly compares with the Forbidden City, but George W. Bush has something in common with the Ming emperors of China: He seems determined to make his great nation less ambitious and more ignorant.

He wouldn't see it that way, of course, but the emperors didn't see it that way either. And I don't know how else to explain policies and pronouncements that make the quest for knowledge conditional on politics. That is a prescription for decline.

In the early 1400s the Ming emperor Zhu Di made China into the world's leading maritime nation, sending huge fleets on missions of trade and exploration as far as the Swahili coast of Africa. It should have been just a matter of a few years before Chinese sailors discovered the Americas. But Zhu Di's successors, influenced by court politics, called home the fleets and forbade them to sail again, forfeiting the riches of the New World -- and five centuries of global domination -- to an underdeveloped backwater called Europe.

I guess it's a general rule of political dynasties, in China as well as in Texas, that the blood thins with successive generations.

Examples? Well, there's the way Bush insists on hamstringing American scientists who are trying to explore the potential medical benefits of therapies involving embryonic stem cells.

You are excused if your eyes glaze over at the mention of the words "stem cells," but it's enough to know that Senate Majority Leader Bill Frist, in a rare display of backbone, has challenged the president over his suffocating restrictions on federal funding for stem cell research -- and also that the fight is akin to arguing over what kind of lock to put on the barn door while the horse frolics in the next county.

While our leaders disagree, stem cell technology is being developed and advanced in laboratories all around the world, especially in Asia. South Korean researchers have arguably pushed farther than anyone else. At the moment it's still a long shot that embryonic stem cells will prove to be a panacea, but if they do it's increasingly likely that the key discoveries will be made elsewhere -- not in the United States.

And there's no real reason for Bush's position except politics. All that Frist and other reasonable people want is to be able to experiment on surplus embryos from fertility clinics, embryos that otherwise will be destroyed. But the radical pro-life lobby won't be reasonable, so Bush does his best to keep the United States on the sidelines of what is, at the moment, the most exciting field of medical research.

Then there's this administration's almost comical insistence that the firm scientific consensus on global climate change is some kind of mass hallucination. "What global warming?" they ask, as mean temperatures rise, Arctic ice melts, tropical diseases march north and hurricanes rake poor Florida in swarms.

The much-maligned Kyoto treaty isn't the point. Treaty or no treaty, it looks as if sooner or later the world is going to have to find a way to prosper without spewing so much heat-trapping carbon dioxide into the atmosphere. Other nations are busy trying to develop technology and coping mechanisms to prepare for that day. When it comes, we'll be at or near the back of the line.

Maybe we'll line up all our obsolete SUVs along the coast to try to hold back the rising sea.

To round out the trifecta, the other day Bush reiterated his support for teaching "intelligent design" in America's schools along with evolution, as a way of exposing students to different points of view. This really borders on madness.

Intelligent design isn't a scientific theory at all; it's a matter of faith -- Creationism 2.0. Faith is a different kind of truth. Charles Darwin's landmark discovery of evolution, with a few minor modifications and additions over the years, has proved to be one of the sturdiest and most unassailable scientific theories of all time. To the extent that science can say anything is true, evolution is scientifically true. Done. Settled. As Walter Cronkite used to say, "That's the way it is."

To teach American children in science class that intelligent design is an alternative explanation of how birds, anteaters and people came to be birds, anteaters and people is simply to make American children less well educated than children elsewhere.

By all rights, we ought to remember the Ming dynasty for discovering America; instead, we think of gorgeous pottery but not much else. China's current leaders seem determined not to make the same mistake.