But these numbers don't tell us why lethal violence is so widespread in the United States. Are we inherently a more violent people than, say, people in Japan,
the U.K., or Slovakia? The UCLA-Harvard researchers, Erin Richardson and David Hemenway, impugn that hypothesis. For when
we examine nonlethal crime and violence rates, the United States is comparable to the other countries studied. The authors
hypothesize that we are an "average" country in terms of violence per se, but that our firearm-related crime rate may be driving
up our non-firearm-related homicide rate. For example, a drive-by shooting by one gang may provoke retaliatory gang killings, using
other means. Importantly, firearms make killing extraordinarily efficient—especially when semiautomatic weapons with high-capacity
clips or magazines are involved, as in the Tucson shootings. An attacker wielding a knife simply cannot take down 20 people
in 30 seconds.