Los Angeles seemed like a good idea at the time. It was a good idea, actually — the setting is spectacular and the weather is perfect. No wonder millions of people decide to live there, and it’s only logical that some of them would build their homes in the canyon-creased hills that look out across the vast urban basin to the infinite sparkling sea.

But every year, some of those canyons will burn. It’s a cycle of destruction and renewal that will inexorably run its course unless humankind intervenes — which means that intervention is a good idea. That means not just moving heaven and earth to put out the fires that do start, but also doing everything possible to keep fires from starting in the first place.

Fire prevention and suppression were so successful that many of the canyons leading up Mount Wilson north of Pasadena hadn’t burned for 40 years or more — until now. And since these slopes haven’t recently been scoured by fire, they are choked with dry chaparral that is like a thicket of tinder, making the conflagration that began over the weekend much worse than it otherwise would have been. The huge “Station fire” — they give them names in Los Angeles — has so far claimed two firefighters’ lives, burned more than 20 homes and scorched at least 130 square miles.

Does this mean we never should have built Los Angeles, or that we never should have listened to Smokey the Bear? Of course not. But it does remind us of how much time and effort we spend dealing with the consequences of decisions that seemed like good ideas at the time.

And I haven’t even mentioned earthquakes.

This is no screed against Southern California. Perhaps an even better example of the burden of a good idea is New Orleans — which, truth be told, looked iffy from the start. The first French settlers realized how precarious the site was, with Lake Pontchartrain to the north and the Mississippi River to the south. Their concern was justified when a hurricane promptly swept in and blew the fledgling town away.

But strategically it had to be a good idea to have a city at the mouth of the continent’s mightiest river, so New Orleans was rebuilt — not for the last time. The city is now marking the fourth anniversary of the Hurricane Katrina catastrophe, which proved something we already knew: that hurricanes routinely enter the Gulf of Mexico and that occasionally a big one will plow into New Orleans.

It has to be a good idea to rebuild the city, since dislocating all those people and abandoning all that infrastructure — and history and culture — would be unthinkable. It has to be a good idea to upgrade the levees and floodgates, and it would be an even better idea to build some kind of enormous, state-of-the-art, Netherlands-style barrier that would offer more protection. But it would be a terrible idea to pretend that there will never be another direct hit by another big hurricane — or that New Orleans, much of which lies below sea level, can ever be made absolutely safe.

And I haven’t even mentioned climate change, sea-level rise and the predicted increase in “extreme” weather events. Like big hurricanes.

Perhaps we can never fully predict the consequences of our good ideas. There was a time when nuclear power looked like the greatest thing since sliced bread. Then came Three Mile Island and Chernobyl, and using nuclear reactors to generate electricity looked like a horrible idea. Now that we’re aware of what burning fossil fuels has done to the climate, even some environmentalists have concluded that maybe it’s a mistake to take the nuclear option off the table.

But, of course, there’s the matter of where to put the nuclear waste. If Yucca Mountain gets ruled out, some other place will have to be ruled in.

In the end, the least we can do — and, probably, the most we can do — is try our best to envision which of our good ideas seems most likely to burden future generations. Should we be seriously limiting coastal development? Will capturing carbon emissions and storing the stuff underground create new problems for our grandchildren to solve? Is there anything in the works, in other words, that’s the equivalent of building one great city that regularly burns and another that regularly drowns?

Eugene Robinson’s e-mail address is eugenerobinson(at)washpost.com.

© 2009, Washington Post Writers Group

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