Do Concealed Guns Reduce Crime?

ByJohn Allen Paulos

Mar. 1, 2001 -- More Guns, Less Crime sounds like an oxymoron, but it is the title of aprovocative book by economist John R. Lott.

The thesis of Lott's book and of the nationwide crusade associated with itis encapsulated in its title: Lott maintains that counties in the UnitedStates that have enacted laws freely allowing for the carrying of concealedhandguns have seen a decrease in confrontational crimes such as murder,assault, robbery, and rape.

Gun as Defensive Tool

Now senior research scholar at Yale's School of Law, Lott has received aninordinate number of kudos and brickbats for his work, which was firstpublished in 1998. He has been called everything from a tool of the gunlobby to a courageous challenger of political correctness.

These are odd ways to refer to someone whose book and papers are full ofarcane statistics and multiple regressions.

The last term is important. A multiple regression is a study of the linear relationship between adependent variable (in this case the crime rate) and a collection ofindependent variables (in this case many factors, including the concealedgun laws, that might affect the crime rate). It attempts to estimate howmuch each of the independent variables affects the dependent variable andhow sure we can be of each of these effects.

The size of the effects is often expressed in terms of so-called regressioncoefficients and our confidence in them involves various other common statistics. Thus many of Lott'scontroversial results (in the book and in his paper on the same subject with DavidMustard) take the dry form of statements about coefficients and confidenceintervals.

If Lott's thesis is correct, regression coefficients relatingconfrontational crime rates to the passage of laws that require officials toissue concealed weapon permits are negative. That is, more guns, less crime. The values ofthese coefficients are also statistically significant, not likely to haveoccurred by chance.

Does Threat Convince Criminals?

I'll spare you the technicalities. Suffice it to say that Lott's formalcalculations are not wrong in any blatant way. He has, however, beencriticized on many other grounds. Researchers Dan Black and Daniel Naginhave, for example, found that Lott's results are less compelling if smallcounties under 100,000 people are not considered. The small counties oftenhave no arrests for certain offenses and so the arrest rate for theseoffenses, one of the many other independent variables in Lott's study, is anunusable value of 0/0.

Others say that Lott's model does not adequately take into account crime trends or unusual situations. For example, the whole state of Florida should have been eliminated from consideration, some argue, because of special problems having to do with Castro's Marial boat lift of 1980 during the term of the study. Critics also maintain that Lott makes no distinction between the crimes of juveniles and adults, that concealed gun laws are not an all-or-non variable, that their effects should vary by state, and that more attention should be paid to the time they've been in effect.

Using data from the 3,054 counties in the U.S., Lott addresses most of theseand other issues with some success in my opinion. But more fundamentalquestions remain.

The most basic is: What is the mechanism for this correlation between moreconcealed weapons and less confrontational crime? In one word: why?

His basic argument is that the increased cost to would-beperpetrators (i.e., the risk of being caught or shot) convinces them to refrain from murder, rape, robbery, andassault. Guns used defensively, or even the prospect of guns being useddefensively by potential victims, is enough to scare some criminals intopursuing less violent careers.

Hot Chocolate Consumption and the Crime Rate

But people with permits for concealed guns are presently those whose workputs them at increased risk or else people who are prudent, but fearful.What would happen if concealed weapons became the norm? Just because acertain relationship (more guns, less crime) is linear and negative oversome range of the independent variable doesn't mean it will remain so over amuch bigger range.

And even if this negative linear relationship were to hold up with many morepeople carrying guns, do we really want to decrease the crime rate in thisway? There is a considerable psychic cost to being a citizen in a nation ofarmed people warily navigating their way through their crime-free lives.Some version of the somber anxiety that one experiences going throughairport luggage scanners would extend throughout one's whole life.

There remain also the usual problems associated with all correlations andregressions. Is the association, even if real enough over a limited range, acausal one or is it coincidental? Or might there be a factor, not yetidentified, leading both to more concealed gun laws and lower crime rates? Afterall, more consumption of hot chocolate is also associated with less crimeand both are brought about by cold weather.

The bottom line is that our understanding of crime rate fluctuations isstill very murky. Why the sudden precipitous drop in the murder rate in NewYork City, for example — the economy, demographics, enforcement? Culturalfactors, while hard to quantify, certainly play an important role.

Some countries like Japan have few guns and little violent crime, whereasothers have few guns and a lot of crime. Similar variation holds incountries with a lot of guns (or should I say a Lott of guns). InSwitzerland and Israel a very high percentage of citizens have guns and thecrime rate is low, whereas in this country many people have guns and thecrime rate is high (although down considerably from its peak).

Although the iconoclasm, statistical presentation, and simplicity of thebook's sales pitch are appealing, I simply don't buy it.

Professor of mathematics at Temple University, John Allen Paulos is the author of several best-selling books, including Innumeracy and A Mathematician Reads the Newspaper. His Who’s Counting? column on ABCNEWS.com appears on the first day of every month.

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