The real problem I have with the study is that the numbers are absurdly unrealistic. 10 murders prevented? I might be able to accept the idea that every two executions prevent one murder or some similarly modest number, but 10 murders for every execution not performed is absolutely absurd. That would suggest that states without the death penalty should have enormous murder rates--and that simply isn't the case; in fact, they tend to be below average.
It sounds like a pseudo-scientific study that found what it expected to find because it expected to find it.
Correlation of variables A and B can mean three things:
1) A causes B,
2) B causes A, or
3) something causes both of them.
OK, so we have a correlation between high murder rates and executions for murder. Our options:
1) high murder rate causes death penalty
2) death penalty causes high murder rate
3) something causes both the death penalty and the high murder rate
This study (once properly peer-reviewed and followed up on) basically says that option 2) is flat wrong. Indeed, if option 1) is the case then states without the death penalty won't have high murder rates (if they did, they'd have the death penalty).One study doesn't convince me of anything, including that 1) is false (though I'm not inclined to say 1) is true, either). But let's refute your point anyway.
It would still make sense--if the standard argument against the death penalty in states without it were that there aren't enough murders to justify it. But that's not the case; it's usually argued on a humanitarian basis and occasionally on a financial basis but never on a "we don't need it" basis.
Consider how many executions happen per year in Texas. Do you really think that Texas would have had
3,900 more murders, including 120 more just so far this year, without the death penalty? That number is ridiculous!
Moreover, Texas used to execute peole on an average of 4 per year in the 1980s. Now it executes an average of 20 people per year, but its murder rate has gone up, not down. The study suggests that the murder rate should have dropped dramatically as the execution rate rose, but clearly this isn't the case. Option 3) is sounding better and better.
If there's no causation involved, then this study is wrong, and clearly the death penalty
does not deter murders. You just proved my point rather than disproving it.
