For this reason, Gary Kleck (who strongly believes that armed citizens deter crime) does not think it likely that the carry law caused crime to decrease. He writes 
Lott and Mustard argued that their results indicated that the laws caused substantial reductions in violence rates by deterring prospective criminals afraid of encountering an armed victim. This conclusion could be challenged, in light of how modest the intervention was. The 1.3% of the population in places like Florida who obtained permits would represent at best only a slight increase in the share of potential crime victims who carry guns in public places. And if those who got permits were merely legitimating what they were already doing before the new laws, it would mean there was no increase at all in carrying or in actual risks to criminals. One can always speculate that criminals' perceptions of risk outran reality, but that is all this is--a speculation. More likely, the declines in crime coinciding with relaxation of carry laws were largely attributable to other factors not controlled in the Lott and Mustard analysis.