What I'm looking for is an accurate analysis of whether or not gun bearing by ordinary citizens results in a net decrease in violent crimes due to a deterrence effect. Articles are very difficult to find. It looks like we may need to examine Kleck (1997)for a comprehensive review. Even so, I'm afraid the conclusions will prove to be indeterminate.

I hope this is more to your liking.
.........

2. Theory.
A basic sketch of the theoretical relations among the three target variables is that
crime is a function of guns and sanctions. The theoretical signs on the partial derivatives
are subject to some dispute. It is generally recognized that prison incarceration reduces
crime due to a combination of incarceration and deterrent effects (e.g., Moody and
Marvell, 1994, 1997, 1998, Levitt, 1996). We would therefore expect a negative partial
derivative on prison in the crime equation. The theoretical sign on guns in the crime
equation is much more controversial. Guns could cause crime because the more guns
there are, the more will fall into the hands of criminals through loss, theft, etc. (Duggan
2000) and more guns in the home or in public will lead to an escalation of violence,
making crime more likely and more serious. On the other hand, Lott and Mustard (1997)
find that the passage of right-to-carry concealed weapons laws, which presumably
increases the number of guns both at home and in public, causes crime to decrease. The
theory is that if a potential criminal is not sure which of a distribution of potential victims
can defend themselves efficiently with a gun, the criminal is likely to be deterred from
committing any crime involving face to face contact with such a potentially armed
populace. It is entirely possible that both arguments are correct and the net effect of guns
on crime could be positive, negative, or zero. Similarly, both arguments could be wrong
and guns are completely independent of crime, yielding a zero coefficient on guns in the4
crime equation. Thus, the sign of the partial derivative of guns in the crime equation
remains an empirical question. See Kleck (1997) for a thorough review of the literature.
Crime can also cause ordinary citizens to acquire guns for self-defense. Thus we
would expect that the partial derivative of crime in the gun equation is nonnegative.
Society attempts to control crime through the use of sanctions. The criminal justice
system includes the police who investigate crimes and make arrests, prosecutors and
judges who try the accused and sentence the guilty, and prisons where convicted felons
are incarcerated. We expect that crime is negatively related to sanctions and that prisons
are positively related to arrests. We assume that arrests and the prison population are
independent of the level of guns except indirectly through possible impacts on crime
1
.
Assuming a linear model, the specification is as follows.
0 1 2 3 4
0 1 2 3
0 1 2
0 1 2
C
P
G
A
C P G A Z
P C A Z
G C Z
A C Z
α α α α α
β β β β
γ γ γ
δ δ δ
= + + + +
= + + +
= + +
= + +
(1)
where C is crime, P is prison incarceration, G is gun availability, A is arrests; ZC, ZP, ZG
and ZA are vectors of exogenous variables, andα1 3 1 2 1 1
< 0, 0, 0, 0, 0, 0 &#945; &#946; &#946; &#947; &#948; < > > &#8805; > .
The sign on &#945;2 is not known a priori.

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