ight now most Americans are focused on punishing the perpetrators. But Tuesday's tragedy was partly self-inflicted. Why did we leave ourselves so vulnerable?

For this is a tale not just of villainy, but also of penny-pinching that added up to disaster ・and a system that encouraged, even forced, that penny-pinching. It's a problem that goes beyond terrorism. Something is amiss with our political philosophy: we are a nation that is unwilling to pay the price of public safety.

In retrospect, our national neglect of airport security boggles the mind. We've known for many years that America was a target of terrorists. And every expert warned that the most likely terrorist plots would involve commercial airlines.

Yet airports throughout the United States rely on security personnel who are paid about $6 an hour, less than they could earn serving fast food. These guardians of our lives receive only a few hours of training, and more than 90 percent of the people screening bags have been on the job for less than six months.

It didn't have to be that way. Last year a report by the General Accounting Office castigated the state of U.S. airport security, comparing it unfavorably with the systems of other advanced nations. In Europe, the people screening your bags are paid about $15 an hour plus benefits, and they get extensive training. Why didn't the United States take equal care?

The answer is that in Europe, airport security is treated as a law-enforcement issue and paid for by either the airport or the national government. In the United States, however, airport security is paid for by the airlines; not surprisingly, they spend as little as possible. Don't blame them ・the fault lies in ourselves, for depending on private companies to do a job that properly belongs in the public domain.

There have been many proposals over the years to put the job in the right hands. For example, in 1997 Robert Crandall, chairman of American Airlines, proposed a national nonprofit corporation to handle airport security. But such proposals went nowhere. They were too much at odds with the spirit of the times, which was all about shrinking the role of government, not expanding it.

And the spirit of the times was definitely against anything that looked like an increase in government spending, unless it was explicitly military. If you look at the sad history of precautions not taken, again and again sums of money that now look trivial were the sticking point. Back in 1996 a government advisory committee on airline security recommended spending $1 billion per year ・about $2 per passenger ・on improvements. The panel rejected the idea of a special airport tax to pay for these improvements, arguing that since this was a national security issue, the money should come out of general tax revenues. But officials at the Office of Management and Budget warned that the committee had "unrealistic expectations regarding the outlook of discretionary funds" ・that is, don't expect politicians to come up with the money. And they didn't.

This is an issue that goes well beyond terrorism. Last year Laurie Garrett, the author of "The Coming Plague," followed up with a chilling book titled "Betrayal of Trust: The Collapse of Global Public Health." The story she tells is ominously similar to that of airport security: a crucial but unglamorous piece of our public infrastructure has been allowed to fray to the point of collapse ・partly because we have relied on the private sector to do the public sector's job, partly because public agencies have been starved of resources by politicians busily posturing against "big government." Don't be surprised if it turns out that we have left ourselves as vulnerable to an attack by microbes as we were to an attack by terrorists, and for exactly the same reasons.

I hope we bring the perpetrators of last week's attack to justice. But I also hope that once the rage has died down, Americans will be willing to learn one of the key lessons of last week's horror: there are some things on which the government must spend money, and not all of them involve soldiers. If we refuse to learn that lesson, if we continue to nickel-and-dime crucial public services, we may find ・as we did last week ・that we have nickel-and-dimed ourselves to death.