“Life is risky. You can decide to, you know, live your life afraid of that happening, or you can decide to live your life the way Americans live their lives, which is unafraid.” So said New York Mayor Rudolph Giuliani two weeks after terrorists turned a swath of lower Manhattan into a mass grave and life as we know it upside down.

As we emerge from the shock of September 11, America is grappling with dual challenges that are pulling us opposite directions: the need to reclaim a measure of normalcy in our daily lives and the need to confront the reality of a world more dangerous than we reckoned.

What measures would make us safer, rather then play into our paranoia?

The blow to our sense of security hit particularly hard in Massachusetts. Loading up two of the airliners-turned-suicide-bombers largely with local passengers and New England-based flight crews, the Bay State suffered the greatest loss of life outside the New York and Washington, DC, attack targets. Though security experts have warned for years of the threat of terrorist acts on US soil‹and we have lived through terrorist attacks in Oklahoma City in 1995 and at the World Trade Center in 1993–the sheer scale of the loss from September 11 has catapulted that risk to a new prominence in our minds. And how high a threat rises “on our radar screen” affects perception of risk as much as the actual danger it poses, says David Ropeik, director of risk communication at Harvard’s Center for Risk Analysis.

“Statistically, the risk of terrorism today is no different than it was” the day before the devastation, says Ropeik. “Our fear of it, however, is universes beyond where it was before those planes crashed.”

So what measures would make us safer, rather than play into our paranoia? In the days following the attacks, some downtown Boston buildings suddenly set up security checks at their main entrances. But gaping holes in the security blanket thrown over some buildings made the moves seem more cosmetic than meaningful.

Airport security has become a prime focus of attention, for obvious reasons. Proposals have ranged from a federal takeover of passenger and baggage checks now performed by contracted security companies to steel doors on airliner cockpits to a demand by pilots to carry guns. But some experts say we can’t afford to dwell only on the hazard we’ve experienced.

“Hijackers and the airplanes and the bombings‹that was the last war,” says William Banks, a national security and counter-terrorism expert at Syracuse University College of Law. The next campaign of terror, he says, may be biological, chemical, or even radiological. It is just that line of thinking that has turned attention to the Quabbin Reservoir, locked up tight after it was buzzed by two airplanes days after the attacks, and other targets of newly conceivable mayhem.

But with danger lurking in the banal, where do we draw the line? At Fenway Park, fans are now banned from carrying coolers into the bleachers. Will coolers also be banned along the Charles River on July 4, when hundreds of thousands of people descend on the Esplanade to enjoy a day of picnics, the Boston Pops, and Independence Day fireworks? And if they are, will that make us safe?

Not necessarily. “If you ban coolers, you certainly don’t prevent someone from having an equivalent amount of dynamite strapped to their body under their shirt,” says Arnold Howitt, director of Executive Session on Domestic Preparedness, a joint project of Harvard’s Kennedy School and the US Department of Justice.

“We can’t get absolute protection by clamping down on everything we could think of, and radically changing everything about American life,” says Howitt. “You can always invent other threats.”

Because those bent on terror‹especially those willing to lose their life in the process–can always find new ways to wreak havoc, the most effective weapon may be knowing when and where such acts are set to occur.

“The single most important thing to do” is ensure that our “information gathering capacity is fully up to speed,” says US Rep. Barney Frank (D-Newton). Frank, a member of the House Judiciary Committee considering proposals to expand the government’s surveillance powers, wants any new laws to include strong safeguards against abuse of those powers. But he acknowledges that the added security will come at a price.

“I think there will be no loss of liberty,” says Frank. “I think there will be a diminution of privacy.”

As we struggle to achieve a balance between returning to familiar routines and making new concessions to a suddenly more dangerous world, it will be important to remember that living with a new degree of danger should be just that.

“Unable to actually imprison us, these terrorists want us to imprison ourselves,” New York Times columnist Thomas Friedman wrote two weeks after the attacks. “When I get on a plane at the airport, frankly, you can X-ray me until I glow in the dark, but I hope we are not heading for a day where we permanently do the same at ballgames and concerts.”