Death Penalty Deters Murders, Studies Say

[Hector]

As far as I can see this is entirely about statistics. These stats don't seem to be very robust.

Mike

Just so.

Perhaps they should go out and execute people at random and see whether there is any change in the statistics.

Oh, they do...

[carlos]

It seems that murdering private citizens is a State's
prerogative. That's the theory of Adolf and Joseph.
All you need is a law allowing it. And if later on you
find that the victim was Innocent, you always can
apologize. Or not at all. After all, you can invoke
"national security" reasons.

[MishaK]

This is the fundamental weakness of any statistical regression model.  You can find a correlation with statistical methods, but you can't "point the causal arrow".  However, this would seem like one case where it is pretty hard to argue that the arrow points in the opposite direction.   One would have to believe that fewer murders or murderers somehow lead to stricter death penalty laws, tougher judges and juries, etc.

Or there could quite simply be a host of other variables at play that the statistcs don't test and don't reflect. You can't just look at two variables and try to figure out which one is cause and effect unless you have definitively shown that no other variable has an impact on your data.

[Bunny]

I am very skeptical of any research that purports to "prove" that an execution means that 5 or 10 or any random number of murders in the future will not occur.  I don't believe that anyone murders in contemplation of the death penalty.  More likely, a murder is done impulsively which means that the killer isn't thinking about consequences.  If someone plans a murder, they go to great lengths to prevent their arrest and conviction, whether the penalty is death or imprisonment.  In fact, those who commit murder by design usually do it because they feel they won't get caught, not that if they are caught they might get the death penalty rather than life in prison.  The logic just doesn't hold water for a study like that!  The one thing I have learned in my life is that statistics and data can be manipulated to support numerous and contradictory conclusions depending on who is doing the analysis. 

That doesn't mean that I am completely opposed to the death penalty, but I see it as a form of justice, not as a deterrent.  Frankly, there are crimes that are so hideous, and those that commit them are so incapable of redemption, that I don't have a shred of compunction in sending them to death row.  I just want to be very sure that the man who gets executed really did commit the crime and so far our legal system hasn't proved to be flawless.  Or, I would prefer that the burden of proof in death penalty cases be higher than for other criminal  cases, beyond reasonable doubt must become without any doubt.

[Redbeard]

Or there could quite simply be a host of other variables at play that the statistcs don't test and don't reflect. You can't just look at two variables and try to figure out which one is cause and effect unless you have definitively shown that no other variable has an impact on your data.

True.  I'm sure they looked at quite a few variables beyond the two being discussed (demographic make up, etc), but this doesn't mean they didn't miss something.  I don't know anything about this study beyond the reference in the OP, and honestly don't plan on changing that.  However, if the study methodology is otherwise sound (proper sampling, design, etc), then critics should really either offer a plausible explanation of why lower murder rates might cause a tougher criminal justice system (seems unlikely), or suggest what untested variable might have explained this apparent correlation. 

[Redbeard]

That doesn't mean that I am completely opposed to the death penalty, but I see it as a form of justice, not as a deterrent. 

This is why in the end the study cited is really meaningless.  Those who support the death penalty do so because they feel it is just, and those who oppose it do so because they feel it is unjust.  No amount of study regarding deterrence will change most people's position.  I happen  to support the death penalty (like you with reservations about the possibility of executing the innocent), and I also happen to believe that there is some deterrent value to it.  However, these two beliefs don't have to go hand in hand.  Alternately, if I believed it was unjust I could still believe in a deterrent effect and not support it. 

[mahlertitan]

took 'em long enough to figure out the correlation.

[Bunny]

took 'em long enough to figure out the correlation.

If there really is a correlation.  More likely, the study was framed in such a way so that the results would support the thesis.  I'm sure that the anti-death penalty lobby could fund another study as well done that would show that the death penalty  actually encourages murder (kill the witnesses to the crime, kill accomplices, etc.), and another group could find the stats to show that there is no correlation at all.  Social science is not hard science.  For a study like this there are no controls, so the results of statistical analysis need to be so strong that they cannot be denied. 

The easiest way to test this theory is to ask if the murder rate in countries that don't have the death penalty is higher than in countries that do.  Is the murder rate in Great Britain substantially higher than in the USA?  I'll bet it's not, and in UK, there is no death penalty.  Is the murder rate in Russia where they have the death penalty lower than in the Netherlands where they don't have the death penalty?  Have the rates of violent crime risen in UK and France as a result of eliminating the death penalty?  Do more Swedes commit murder than Egyptians because there is no death penalty in Sweden and there is a death penalty in Egypt?

After someone demonstrates that the murder rates in Sweden, UK, Netherlands, France, Spain, Belgium, Italy, et al. are higher than in Virginia, New Jersey, Georgia, Alabama, North Carolina, New York or California then perhaps I'll give some serious consideration to this study.  Until then, it's just words written on paper to advance a political agenda.

[The new erato]

Why don't they study whether an absence of guns in the general population has any effect on the murder rate? For me it seems that there would be a far more obvious connection here?

Which goes to show that this is a heavily politically biased study.

[BachQ]

Why don't they study whether an absence of guns in the general population has any effect on the murder rate?

There are many.  One study concludes "that many lives would be saved if all states increased their level of control to that of New Jersey, the state having the most stringent gun control laws."

See also, e.g., Murray, Handguns, Gun Control Laws and Firearm Violence, 23 SOC. PROB. 81, 88-91 (1975); Cook, The Effect of Gun Availability on Violent Crime Patterns, 455 ANNALS 63 (1981); Zimring, Is Gun Control Likely to Reduce Violent Killings?, 35 U. CHI. L. REV. 721 (1968).

[The new erato]

Thanks! Still I notice no lack of guns chez the Sopranos.....

[Bunny]

Thanks! Still I notice no lack of guns chez the Sopranos.....

Yes, but there is no chez Soprano anymore -- and who even knows why...

[mahlertitan]

what next? whether incarceration deters crime?

[Hector]

what next? whether incarceration deters crime?

Some would argue that it doesn't but others would say, so what if it doesn't because it is a punishment.