The Death Penalty, Deterrence in Practice

In Part 1 of this series, I dealt with the plausibility of the model in favour of Deterrence. But let’s forget all about that for a moment. Let’s put aside all the science behind our decision processes, how the human brain works, and all of that stuff. Like Deterrence-advocates, let’s pretend that science hasn’t moved since, I don’t know, the early 1900s.

To recap:

The Deterrence argument is relatively simple, and is based on a very simple model of human psychology and behaviour: people don’t like bad things to happen to them. Pick a behaviour that you want to modify, introduce a penalty for it and the incidence of that behaviour will decrease. Additionally (and yes, this is a separate thing), increasing the degree of the penalty will further decrease the incidence of the behaviour.

Now the important thing to notice here is that this is a model for human behaviour: if we change x about the world, then y about the world will also change. It’s a relatively simple thing to test for, and as such the only thing that matters here are the consequences: do people act in the manner predicted, or not? If they do: then we keep doing what we’re doing. If they don’t: then the model has failed, and the primary argument is false. That’s all there is to it.

It turns out that causality is a pretty tricky thing to measure, and that there’s a bunch of studies put forward as supporting the causal connection. I believe in putting the best case forward, so rather than provide you with links to the holy-shit-terrible newspaper articles that people inevitably provide me with, you should check out the holy-shit-terrible academic studies instead. And look, to be fair, demonstrating a causal relationship between a law and social behaviour is really damn hard. Finding the Higgs Boson? You just build a super-huge collider, and it’ll pop out eventually. Demonstrating that a law passed in a certain year is responsible for x less murders since that point? I’ll be betting on the local chemtrails guy supporting their claim before you.

The bar for rigour must be  exceptionally high: on the table is State-sanctioned killing. You want to argue that the State, with all its imperfections, prejudices and outright racism gets to kill citizens with impunity, then you need to create a case so airtight that it cannot be argued against. Ignoring all other possible explanations (as most all of those studies do) because ‘science is hard’ is unacceptable.

So here’s the thing: I can articulate what kind of study would convince me that the deterrence effect is real. I want a study that takes account all of the possible variables including, but not limited to, socioeconomic background, upbringing, cultural factors, religious background (which could well be folded into the previous two variables, I’m flexible), and variation across international lines. Account for all of that, and show me that even controlling for all of those things that a reduction in sexual offense and murder highly positively correlates with the death penalty (no, correlations between muggings and longer sentences doesn’t cut it, that’s a different flavour of crime), and then and only then you have my attention.

That’s too hard?

Oh, my bad, I thought you were trying to do Science.

None of the studies on deterrence come even close to demonstrating a positive practical effect, and one would presume that that’s a serious problem for the advocates of deterrence. Simply saying ‘here’s a law that increased penalties for crime, and in the years subsequent, crime went down’ is ludicrously insufficent: in order to attribute the change to the law, all other possibilities must be either excluded, either logically or by accounting for their effects.

Furthermore, advocates can’t simply look at the states where it allegedly works, they need to answer for Texas: this state has a death penalty rate of almost five times the next highest state (in absolute numbers). Surely at this point Texas should be crime free? Yet it’s incidence of crime is about what all the other states are at, including those states without the death penalty. Here’s a fun fact: “For 2011, the average Murder Rate of Death Penalty States was 4.7, while the average Murder Rate of States without the Death Penalty was 3.1”. Are Texans (and others) just SO bloodthirsty that the death penalty is bringing their murder rate down to it’s current way-above-average levels? Citation needed…

This, of course, is in addition to the point that an exceedingly high and disproportionate number of people put to death in the US are people of colour. The death penalty in that particular country is a stark illustration of the effects of systemic racism, and any argument in favour of deterrence (on practical grounds) needs to respond to that.

So on the practical side, there are two problems:

  1. There is zero evidence in favour of the existence of any kind of deterrence effect
  2. There is a whole pile of evidence against the existence of any kind of deterrence effect

And we’re done.

Part 1: The Death Penalty, Deterrence in Principle
Part 2: The Death Penalty, Deterrence in Practice
Part 3: The Death Penalty as Retribution
Part 4: The Death Penalty, The Economic Argument

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