Evaluating anti-gun control arguments #7: Gun ownership has increased over the last 25 years, while gun violence/crime has decreased over the same time. This proves that more guns do not cause more violence/crime.

Argument: Gun ownership has increased over the last 25 years, while gun violence/crime/homicide has decreased over the same time. This proves that more guns do not cause more violence/crime/homicide, and, if anything, proves that they do the opposite (as per the title of the (in)famous book "More Guns, Less Crime").

Example: "...the number of guns per American increased from 0.93 per person in 1993 to 1.45 in 2013, which is a 56% increase in the number of guns per person that occurred during the same period when gun violence decreased by 49%." -American Enterprise Institute

Response: 
The claim that an increase in rates of gun ownership in the US in recent decades has coincided with a decrease in homicide and other violent crime rates over the same time is made very often by those opposing gun control. That this is so makes sense because this seems to indicate that more guns = less crime, as many, if not most, gun rights activists believe. 

The problem with this claim isn't with the part that says that crime & homicide have declined in the US significantly in the last 25 years or so--there is little doubt that this is the case (e.g. Levitt 2004). The problem is with how "gun ownership" is defined--usually either the total number of guns in the U.S. or, as in the AEI post linked above, the number of guns per person. Both of these figures have indeed increased significantly in the past several decades, but during the same time period, the % of households with (a) gun(s) has dropped significantly, as has the % of adults that personally own any gun(s) (Washington Post 2016, NORC 2015).

Why have these trends been going in opposite directions in the past several decades? Zimring (2017, p. 11) pointed out that "These two trends could coexist if most of the new guns introduced into the civilian market are purchased by persons who already own guns." He also notes that "If the increase in guns hasn’t been accompanied by an increase in rates of personal or household ownership, it should not be expected to produce a major increase in the proportion of violence that involves gun use" (Huffington Post 2017). 

References:
Huffington Post 2017
Levitt 2004
NORC 2015
Washington Post 2016
Zimring 2017