Lott/Mustard Debate

[Originally posted to firearmsreg Aug 16 1996]

Daniel Polsby writes:

Mr. Lambert, and for that matter most others on this list, assume
that firearms are used defensively when they are brandished. All of
the endless back and forth about survey research techniques of
establishing how often this sort of thing happens has embedded this
assumption.

No, my comments were directed specifically at the deterrence
theory. IF concealed weapon permit holders used their weapons
frequently (say two or three times a week) and IF these incidents were
given wide publicity (so that criminals were made aware of the risk
they faced) THEN you would have a plausible mechanism by which a
concealed wepons law could cause a large decrease in crime.

Economists’ model of deterrence treats the prospect of
meeting armed resistence as affecting, ex ante any misbehavior, the
apparent present value of a given crime. The prospect of meeting an
armed defender or an armed good Samaritan should be expected to do
two things: (1) raise the absolute expected cost of confrontational
crimes and thus (2) increase the relative value of other potential uses
of ones time, including non-confrontational crimes.

Compare: 2 encounters with armed CCW holders per year in Dade county
with 10,000 arrests by armed police for violent crime per year in Dade
county. The chance of meeting an armed CCW holder is negligble. In
an economic model of deterrence it will be swamped by the 5,000 times
greater chance of being arrested.

Incidentally, in case the point has been lost, I have never
questioned the integrity or seriousness of McDowall and his collaborators.

Pardon? You accused McDowall et al “of taking the extra steps necessary to
locate a subset of the data that would yield a particular result.”
It certainly sounds to me that you are accusing them of dishonest data
selection.

Suffice to say that no
conversation about causation and correlation can be had without a
reasonable grasp of David Hume’s argument on this subject, which was,
in brief, that “causation” as such can never be demonstrated. How do
you know, if you drop a marble, that your dropping of it has “caused” it
to go onto the floor? How do you know that this result is not,
simply, highly correlated with dropping?

Absolute certainty is of course impossible. Scientists generally
accept a replicable controlled experiment as good enough for showing
cause and effect for practical purposes. A non-experimental study
like Lott’s is merely suggestive of causation. When you have a pile of
them and well-understood and verified mechanisms (like for
smoking-cancer) then you can maybe make some causal claims. Lott says:
“If those states which did not have right-to-carry concealed gun
provisions had adopted them in 1992, approximately 1,570 murders;
4,177 rapes; and over 60,000 aggravate assaults would have been
avoided yearly.” This statement needs at least two caveats that Lott
does not give us.

jmaraldo writes:

Why assume that only the defensive use deters, that the knowledge the
intended victim and civilians in the vicinity may be armed does not also
deter? It seems to me that a shall-issue CCW system is like a sign which
says “Premises Protected By ** Alarm” in that the many more burglars are
deterred than actually trigger the alarm and the sign often works even
though there is in fact no alarm installed.

But CCW holders do not carry signs saying “Person Protected By Smith
and Wesson”. What is it that is telling criminals that they are
facing a risk from CCW holders? It can’t be from personal experience
in encountering one, or media reports of CCW holders thwarting crime,
since these incidents are almost nonexistent.

Tom Tancredo (really Dave Kopel?) writes:

Tim Lambert writes:

It does not seem highly plausible that those two uses prevented 2,000
crimes. “

Sure it’s plausible. First of all, there is some unknown number of DGUs by
permitees that were never reported to authorities. It’s possible
that 90% may be unreported, since there’s no real need to tell the
police that you drew a gun, and the criminal ran away.

If Kleck’s DGU survey is to be believed 64% of DGUs are known to the
police. In any case, even if there are another 20 unreported ones,
these aren’t going to have much of a deterrent effect since only one
or two criminals will be aware of them.

More important, as Kleck has shown in various cases, wide publicity about the
prevalence of armed citizens can sometimes have a huge deterrent
effect, all by itself.

Firstly, I do not believe that Kleck has shown this at all. Publicity
in Orlando and Kansas City was associated with a temporary but not
statistically significant reduction in crime. His arguments about
Kennesaw are not even internally consistent.

Secondly, if the mechanism to be invoked is that publicity about the
introduction of CCW laws reminded criminals of the risks that they
faced from armed victims, then Lott has used the wrong model. Such an
effect would be as temporary as the publicity, so his model should be
for a temporary effect, not a permanent one.