Skip to main content

In school rampages, the weapon matters

By Philip J. Cook and Kristin A. Goss
updated 11:22 AM EDT, Fri April 11, 2014
Parents and students embrace near Franklin Regional High School, where authorities say at least 20 people were injured in a stabbing spree Wednesday, April 9, in Murrysville, Pennsylvania. Parents and students embrace near Franklin Regional High School, where authorities say at least 20 people were injured in a stabbing spree Wednesday, April 9, in Murrysville, Pennsylvania.
HIDE CAPTION
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
Stabbings at Pennsylvania high school
<<
<
1
2
3
4
5
6
7
8
9
10
11
12
>
>>
STORY HIGHLIGHTS
  • Authors: Injury, not death, came from school stabbings in Pennsylvania
  • They say research has long found for purposes of life and death, the weapon matters
  • Writers: Deaths from gun attacks higher than those from knives, other weapons
  • If public policy led to reduction in gun use in crimes, murder rate would go down, they say

Editor's note: Philip J. Cook is ITT/Terry Sanford Professor of Public Policy, and Kristin A. Goss is associate professor of public policy at Duke University's Sanford School of Public Policy. They are co-authors of "The Gun Debate: What Everyone Needs to Know," published this month by Oxford University Press. The opinions expressed in this commentary are solely those of the authors.

(CNN) -- It rarely makes sense to draw big conclusions or make public policy on the basis of anecdotes. But the plural of "anecdote" is data, and sometimes one-off events are useful in crystallizing lessons to guide policymakers and inform the public.

So it was with the Pittsburgh-area rampage this week in which a teenager bearing two kitchen knives is accused of injuring 21 high school classmates and a security guard -- but none of them were killed. It's hard to imagine an anecdote that better illustrates what decades of data show: that for purposes of life and death, the weapon matters.

It's called "the instrumentality effect," and we owe the original scholarly findings (more than four decades old at this point) to the eminent University of California criminologist Franklin Zimring. Others, including one of us (Cook), have validated and built upon his insights.

Kristin A. Goss
Kristin A. Goss

The idea that the weapon matters emerges in studies of robberies and assaults. When committed with a gun, these crimes are far more likely to result in the victim's death than are similar violent crimes committed without a gun. For example, the likelihood that a victim will die when robbed by a firearm-wielding attacker is three times as high as when the victim faces an attacker bearing a knife and 10 times as high as when the attacker has another type of weapon. For victims injured in an assault, the likelihood of death is also greater when a gun is involved, especially in cases of domestic violence.

Of course, the choice of weapon could be simply a product of the perpetrator's focus on killing; perhaps it's this intensity, not the choice of weapon, that is really to blame. In light of Wednesday's knife attacks in Pennsylvania, Zimring's findings are particularly telling.

Heroic acts during Pennsylvania stabbing
Newtown mom reflects on anniversary
Community seeks motive for stabbing

To separate the effects of the weapon vs. the intent of the perpetrator, he looked at fatality rates for different calibers of guns. If perpetrator intent were really to blame, zeroing in on attacks with guns would "control" for that effect. Zimring found, as the instrumentality perspective would predict, that people shot by larger caliber guns -- which carry bigger and more destructive bullets -- were more likely to die than those shot by smaller caliber guns.

Adding more evidence to the case that the weapon matters, Zimring and Gordon Hawkins later demonstrated that overall crime rates aren't that much higher in American cities than in comparable cities in other developed countries. We just have higher rates of homicide, and that is because our criminals are more likely to be armed with guns and thus their attacks are more likely to end in the victim's death.

The most important and interesting implication of the instrumentality effect is that if public policy could reduce gun use in crime, the murder rate would go down -- even if the overall crime rate did not. As it turns out, about half of American states have enacted policies that add prison time to felons who use a gun when committing their crimes.

These so-called sentencing enhancements, most of which were adopted in the 1970s and 1980s, were intended to reduce the use of guns in violent acts. Scholarly evaluations based on data, not anecdotes, offer some evidence that these policy innovations have been effective.

This week's tragedy can't help but invoke memories of the mass shooting at Sandy Hook Elementary School some 16 months ago. The difference today is that, because the Murrysville, Pennsylvania, perpetrator chose to use knives, victims' families can look forward to a future with their loved ones -- instead of planning their funerals.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

ADVERTISEMENT
Part of complete coverage on
updated 2:25 PM EST, Fri November 21, 2014
Maria Cardona says Republicans should appreciate President Obama's executive action on immigration.
updated 7:44 AM EST, Fri November 21, 2014
Van Jones says the Hunger Games is a more sweeping critique of wealth inequality than Elizabeth Warren's speech.
updated 6:29 PM EST, Thu November 20, 2014
obama immigration
David Gergen: It's deeply troubling to grant legal safe haven to unauthorized immigrants by executive order.
updated 8:34 PM EST, Thu November 20, 2014
Charles Kaiser recalls a four-hour lunch that offered insight into the famed director's genius.
updated 3:12 PM EST, Thu November 20, 2014
The plan by President Obama to provide legal status to millions of undocumented adults living in the U.S. leaves Republicans in a political quandary.
updated 10:13 PM EST, Thu November 20, 2014
Despite criticism from those on the right, Obama's expected immigration plans won't make much difference to deportation numbers, says Ruben Navarette.
updated 8:21 PM EST, Thu November 20, 2014
As new information and accusers against Bill Cosby are brought to light, we are reminded of an unshakable feature of American life: rape culture.
updated 5:56 PM EST, Thu November 20, 2014
When black people protest against police violence in Ferguson, Missouri, they're thought of as a "mob."
updated 3:11 PM EST, Wed November 19, 2014
Lost in much of the coverage of ISIS brutality is how successful the group has been at attracting other groups, says Peter Bergen.
updated 8:45 AM EST, Wed November 19, 2014
Do recent developments mean that full legalization of pot is inevitable? Not necessarily, but one would hope so, says Jeffrey Miron.
updated 8:19 AM EST, Wed November 19, 2014
We don't know what Bill Cosby did or did not do, but these allegations should not be easily dismissed, says Leslie Morgan Steiner.
updated 10:19 AM EST, Wed November 19, 2014
Does Palestinian leader Mahmoud Abbas have the influence to bring stability to Jerusalem?
updated 12:59 PM EST, Wed November 19, 2014
Even though there are far fewer people being stopped, does continued use of "broken windows" strategy mean minorities are still the target of undue police enforcement?
updated 9:58 PM EST, Mon November 17, 2014
The truth is, we ran away from the best progressive persuasion voice in our times because the ghost of our country's original sin still haunts us, writes Cornell Belcher.
updated 4:41 PM EST, Tue November 18, 2014
Children living in the Syrian city of Aleppo watch the sky. Not for signs of winter's approach, although the cold winds are already blowing, but for barrel bombs.
updated 8:21 AM EST, Mon November 17, 2014
We're stuck in a kind of Middle East Bermuda Triangle where messy outcomes are more likely than neat solutions, says Aaron David Miller.
updated 7:16 AM EST, Mon November 17, 2014
In the midst of the fight against Islamist rebels seeking to turn the clock back, a Kurdish region in Syria has approved a law ordering equality for women. Take that, ISIS!
updated 11:07 PM EST, Sun November 16, 2014
Ruben Navarrette says President Obama would be justified in acting on his own to limit deportations
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT