When I was 13 or 14, my parents let me take the train from central New Jersey to New York's Penn Station and then transfer to the subway to watch the US Open at Forest Hills. They gave me a lot of safety tips: Don't look lost. Don't get in empty subway cars. Don't talk to strangers. Don't take your wallet out of your pocket. Etc., etc.
One thing they never thought to warn me about was what to do if a bomb went off in the train.
These days, the old anxieties about taking the subway seem almost quaint. In contrast to the perils we worried about in the 1970s, the danger of getting blown up is more remote, but harder to guard against.
That's why Thursday, July 7, the day of the London subway bombings, found me and my wife wondering whether to send our 11-year-old daughter and two of her friends to day camp on the Metro, as we'd done every day for the previous two weeks. On the one hand, as the mother of our daughter's friends said, the higher level of alert here in Washington meant the kids would probably be safer than on any other day of the year. On the other, we couldn't help imagining a similar disaster here.
In the end, we opted to drive. As my wife said later, "The idea of her on the Metro with no adults and having to fend for herself if something happened was too terrible to contemplate."
Most commuters, however, shrugged it off. According to Metro statistics, ridership the day after the bombings was 10 percent below what it had been on the day before them - but July 6 had seen Metro's ninth-highest ridership, and ridership usually dips on Fridays, especially when the Nationals aren't in town. Last week, ridership was back to normal.
After the train bombings in Madrid and London, Washington and its mass transit seem natural targets. Our own government officials often speak of the inevitability of a cataclysmic attack on American soil and the need for more homeland security. But sometimes it isn't clear what those of us in prime target zones are supposed to do about that.
It comes down to risk calculation. If I were being scientific, I might say something like: risk multiplied by frequency divided by life benefits yields a number with an inverse relationship to advisability. Except in this equation, every variable is unknown or unquantifiable.
That doesn't stop us from making guesses, just as we guess about the risks of many other activities. My late father was an orthopedic surgeon, so I avoid skateboarding and ice skating. On the other hand, as a journalist I've flown on a variety of doubtful airlines, covered South Africa's violent black townships during states of emergency, and breathed Beijing's heavily polluted air for four years.
Sometimes risks are apparent only with hindsight. For 3-1/2 years I worked two blocks from the World Trade Center towers. In London, I took the underground to work from the Edgware Road stop, where a departing train was blown up on July 7.
Looking ahead is harder. Since 9/11, my wife and I have talked about whether we needed to recalibrate the risk factor in our lives here. It isn't ideal for both of us to be working within five blocks of the White House, a possible terrorist target.
So when I get on the Metro again and head downtown, it won't be because I'm oblivious to the risks of living in the nation's capital. But I've weighed the likelihood of anything happening against other factors: the privilege of working for a major newspaper, the ability to live in a nice house and run in the park, and the intellectually and culturally stimulating urban environment Washington offers.
The other day I discussed reasonable risk with Courtney O'Connor, the mother of the girls riding on the Metro with my daughter. "I'm not your average parent," she said, explaining why she wouldn't have minded if our kids had taken the Metro. That's an understatement. Ms. O'Connor worked for the United Nations in El Salvador during the war there in the 1980s and has advised peacekeepers in hot spots in West and Central Africa. She's driven by blown-up cars, seen military abuses, and was nearly kidnapped once. "I've lived with violence and have a sense of when you're at risk and when you're not," she said.
When does she think we're most at risk? "When we're not watching," she said. She and her husband are renovating their house for a prolonged stay, but said, "I certainly say to myself that in order to live here and invest in this renovation, you have to be in a little bit of denial about what can happen at any moment."
A little bit of denial can be a good thing, but too much can be harmful. That's the way another friend, fellow journalist Jeffrey Goldberg, thinks of it. He was talking about the "We're Not Afraid" campaign in London, whose popular website claims to "show the world that we're not afraid of what happened in London, and that the world is a better place without fear."
"To say you're not afraid is a form of denial. Admitting you're afraid doesn't mean you don't go outside. But it's foolish not to act on justifiable apprehension," says Mr. Goldberg, who lived in Israel for six years. A little bit of fear - and caution - could make us much safer, he says. He cites the different ways Israelis and Americans react to unattended packages or bags, or to suspicious people.
"In Israel, when you see a package unattended, almost instantly someone will call the police and the police will respond and whole bus stations will be evacuated," Goldberg says. "Ninety-nine percent of the time it's some dope who went to the bathroom. But that person is the one who's scorned. The person who made the call is the hero even if the bag is old underwear. But in America still, I don't think these are behaviors considered acceptable."
Another friend, who worked for the 9/11 commission, agrees. Against a supple and ingenious foe, the most effective defense is a population that's alert in airports and on subways and streets to strange packages or strange people. "Subway riders need to think of themselves as passengers on the flight with the shoe bomber Richard Reid," this friend said.
The New York City Transit Authority is promoting that new attitude with an ad campaign that says: "If you see something, say something." The Massachusetts Bay Transit Authority urges people to report others "behaving oddly" and "people showing visible signs of nervousness, such as excessive perspiration."
As much as President Bush or British Prime Minister Tony Blair say we won't let terrorists change our lives, this could be the start of a new era, and not in a good way. There is something unsettling about the idea of turning America into a nation of snitches and amateur spies. Is the guy taking photos of the George Washington Bridge a terrorist or the next Henri Cartier-Bresson? Are people wandering in front of national monuments scoping out targets or are they tourists? And do you trust the strangers around you to make those judgments based on looks and feelings?
All the same, on the Metro last week, I departed from my usual routine of simply reading the newspaper, or looking over a manuscript, or daydreaming. I found myself glancing up to look at the other passengers and their bags, or to gauge the distance to the stairs, or read the instructions on the emergency exits. Reassuring? Maybe.
In any case, this week you'll be able to find me on the platform waiting for the next train.
• Steven Mufson, deputy editor of The Washington Post's Outlook section, has reported on national security issues as a member of the newspaper's national and foreign staffs. ©2005 The Washington Post. [Editor's note: The original version did not contain the copyright information.]