Boston police and members of the military stand guard on the streets around Copley Square the day after two bombs exploded at the finish of the Boston Marathon. Photographer: Melanie Stetson Freeman/The Christian Science Monitor via Getty Images
Boston police and members of the military stand guard on the streets around Copley Square the day after two bombs exploded at the finish of the Boston Marathon. Photographer: Melanie Stetson Freeman/The Christian Science Monitor via Getty Images

The Boston Marathon bombing, juxtaposed with the mass murder at Sandy Hook Elementary School in Newtown, Connecticut, reveals an ideological component to the way Americans assess risk. In particular, Americans' tolerance of mayhem and death varies depending on the source of the violence.

The Wall Street Journal editorial page, for example, was quick to revisit old fears about foreign terrorism in the wake of the Boston attack:

"The Boston bombing is above all a reminder of the continuing need for heightened defenses against terror threats. As the years since 9/11 without a successful homeland attack increased, the temptation was to forget how vulnerable the U.S. is, and to conclude that the worst is over."

The emphasis on vulnerability and the "continuing need for heightened defenses" represents one side of an existential schism running through U.S. politics, with the dividing line separating mostly, but not always, liberals from conservatives. Many Americans accept the U.S.'s 30,000 gun deaths a year as a sad but inevitable price for all-but-unfettered individual rights to gun possession. A terrorist bombing, on the other hand, signals a need for "heightened defenses," massive security and the routine compromise of liberty (in addition to delays and frustrations) at airports, in cyberspace and elsewhere.

On the other side are people (I'm often one) who chafe at the demands of the terrorism-industrial complex, see hysteria where others see prudence and find the national clamp-down not only misguided but, at its worst, even a bit craven. We weigh the senseless carnage in Boston (death toll thus far: 3) against the senseless carnage of domestic gun violence (annual death toll: 30,000) and wonder why American society mobilizes with such impressive force against the smaller threat while shrugging at the larger one. (Gun violence produces the same number of victims as the Sept. 11 attacks almost every month, year in and year out.)

The Second Amendment is relevant here; but it's not really an answer. Constitutional liberties have been nipped and tucked in the wake of the Sept. 11 attacks without generating much outrage. And the Second Amendment secures a right that, as even the Supreme Court's conservative wing maintains, is subject to regulation and constraint.

Where one falls along this risk divide seems more a matter of psychological disposition than anything else. Sandy Hook ignited the fears of Americans who are mystified by their countrymen's embrace of guns. The Boston Marathon, should it turn out to be something other than domestic terrorism (in which case the anti-gun crowd may begin pointing fingers again), will likely activate the fears of people who stock guns to keep them safe. One American's intolerable violence is another's endurable, unavoidable fact of life.

(Francis Wilkinson is a member of the Bloomberg View editorial board. Follow him on Twitter.)