t would be a great philosophical question in a college course: How much personal freedom should we Americans (and visitors to our country) be prepared to give up to thwart those who would terrorize us. Unfortunately, it's not an academic question but a real world test that Americans, along with other nations, are facing now that a young Nigerian has been foiled in his attempted Christmas Day bombing at the Detroit airport.

The question is being debated vigorously because the government has stepped up its use of full-body scanners, electronic detection devices that subject airline passengers to what amounts to a virtual strip search. They use X-ray technology to (supposedly) detect weapons or chemicals hidden under clothing. Are such tactics an unnecessary invasion of personal privacy or, as the government argues, a necessary protection against terrorism?

Putting aside the privacy issue for now, the government is proceeding with the program. There are 40 body-scanning units in use at 19 airports and the Transportation Security Administration has ordered 150 more of them to be installed early this year and is busy finding funding for an additional 300.

Passengers selected for a full-body scan can decline, but if they do, they must then submit to full-body pat-downs by a TSA officer. The technology has been available for a few years now, but American airports have been reluctant to install the machines, in part because members of Congress and civil liberties groups have raised the privacy concerns. After the Christmas Day incident at Detroit, the need to improve airport security – here and abroad – has become a pressing issue and the subject of considerable debate.

"The price of liberty is too high," says Kate Hanni, founder of FlyersRights.org, an advocacy organization for air passengers. She said many of her group's 25,000 members fear that the full-body scanners may not catch the terrorists but nevertheless "will subject the rest of us to intrusive and virtual strip searches."

Others disagree, pointing out that the controversial body scans are, as their description suggests, virtual. Passengers remain fully clothed and the image the scanner produces appears on a monitor in a separate room while concealing passengers' faces and sensitive areas.

"It covers up the dirty bits," James Carafano, a homeland security expert at the politically conservative Heritage Foundation, told The Washington Post. Brandon Macsata, who launched the Association for Airline Passenger Rights, agreed, saying "I don't think it's any different than if you go to the beach and put on a bikini."

The TSA has launched an effort to persuade passengers that its latest checkpoint practices will make airports more secure, but when Congress reconvenes later this month the issue will almost certainly trigger debate on Capitol Hill. The House has already passed a bill limiting the use of the full-body scanners but the subject has yet to be discussed in the Senate.

Some experts contend that even with full-body scanning explosives can escape detection if would-be terrorists were to conceal them in body cavities. Others protest the fact some passengers are unfairly singled out for special attention simply on the basis of their nationality or on where their flights originated. And some are raising practical concerns, noting use of the devices could create unacceptable bottlenecks at airports.

The White House announced Sunday that citizens of 14 nations flying to the United States will be subjected indefinitely to enhanced screening at airports worldwide. American citizens, and most others not flying through these particular nations, no longer will automatically endure the full range of intensified security imposed after the Detroit scare.

As difficult as it is to strike the proper balance between the rights of individual passengers and the need for effective national security, for now the government deserves the benefit of the doubt.