Does allowing people to own or carry guns deter violent crime? Or does it cause more citizens to harm each other? Wherever people happen to fall along the ideological spectrum, their answers are all too often founded upon mere impressionistic and anecdotal evidence. In this direct challenge to conventional wisdom, legal scholar John Lott presents the most rigorously comprehensive data analysis ever done on crime. In this provocative work he comes to a startling conclusion more guns mean less crime.

In what may be his most controversial conclusion, Lott finds that mass public shootings, such as the infamous examples of the Long Island Railroad by Colin Ferguson or the 1996 Empire State Building shooting, are dramatically reduced once law-abiding citizens in a state are allowed to carry concealed handguns.