[schaefer]

magashna: Punishment is not a deterrent. rbut: Punishment is a deterrent and has been proven ... magashna:murder rates are consistently higher in states with the death penalty. joshuamorton: I doubt this relationship is causal.

Magashna is clearly not arguing causality, but rather that the death penalty has failed to be a deterrent to murder.

[joshuamorton]

This doesn't show that though. You have to examine the counterfactual: would the crime rate be even higher without the death penalty? If yes, it is a deterrent.

[stallmanite]

How can one examine a couterfactual in cases like this? Barring access to Marty McFly’s time machine unless you have two identical copies of a state to experiment on how would you go about this?

Edit: legitimately curious, not trying to be nitpicky

[joshuamorton]

You probably can't, which is my point.

Generally the best ways to analyze the impact of similar social changes is to compare two similar locations, one that makes a change and one that doesn't, over the same time period, and hope that controls for broader social change.

It's not perfect by any means though.