You can get an unambiguous answer, but the answer depends on your assumption:
Under the weakest restrictions, there is substantial ambiguity: we cannot rule out the possibility that having a death penalty statute substantially increases or decreases homicide. This ambiguity is reduced when we impose stronger assumptions, but inferences are sensitive to the maintained restrictions. Combining the data with some assumptions implies that the death penalty increases homicide, but other assumptions imply that the death penalty deters it.
From a new and careful paper. Short answer: we have no idea. But there’s a reasonable chance that it raises homicide rates as much as it lowers them.
If you think (as I do) that the burden of proof ought to be on the proponents of more draconian punishments, well, the burden is not borne.
Of course, like most policy, it’s silly to pretend that this is a debate based on evidence and reason, let alone real deterrence (on either side).
what is the intuition behind the possibility that the death penalty might actually raise homicide rates?
Well criminal law and punishment is about more than deterrence. Retribution is also very important.
As Kant said: “Even if a civil society were to be dissolved by the consent of all its members. . .the last murderer remaining in prison would first have to be executed, so that each has done to him what his deeds deserve and blood guilt does not cling to the people for not having insisted upon this punishment; for otherwise the people can be regarded as collaborators in his public violation of justice.”
There are definitely papers arguing for both sides, however the majority in the last 10 or so years ( that im aware of) have found that it does act as a deterrence so that the position im siding with.
( im aware that the above source is pro-death penalty but it has actually been pretty good so far when it comes to presenting every paper done on the subject for the last decade)
This paper by Daniel Chen seems to show that death penalty wasn’t even deterring enough to prevent british soldiers absenteeism during WWI: http://www.duke.edu/~dlc28/papers/DeathPenalty.pdf
I’m no fan of “burden of proof” arguments—such reasoning is too lexicographic for my taste. What I’d say is that a death penalty applied often enough to make a difference will have to sometimes execute innocent people. In some settings this is deemed an acceptable risk (for example, shooting deserters in wartime), in others not. I think the death penalty only makes sense in the present-day U.S. if people are comfortable with executing some innocent people (Randall Dale Adams, etc).
Translation: I think the burden of proof should be on those protecting the innocent and not on those protecting the guilty.
I’m sure you believe that.
Whatever you may have heard on some TV drama, someone sentenced to 10 consecutive life sentences without parole is no more likely to walk free in public than someone sentenced to the death penalty (less, really, given how the appeals process works), so as far as “protecting the innocent” from the perpetrator in question, your argument doesn’t wash. Also it’s unconstitutional, but whatever.