Published on February 21, 2025 8:30 AM GMTEpistemic status: this is an attempt to steelman the case for the death penalty rather than produce a balanced analysis, or even accurately represent my views (the case is presented as stronger than I actually feel).In a sufficiently wealthy society we would never kill anyone for their crimes. We are not a sufficiently wealthy society.There are those people whose freedom imposes such high costs on society that society should not suffer to have them free.A murderer or rapist not only ruins the lives of their victims, not only causes immense suffering to their victims' families, but frightens people into staying indoors at night, or only going out in groups.A shoplifter might only steal a few hundred dollars of goods, but they force shops to close or lock up all items, causing significant hassle to everyone in the area.A bicycle thief steals a bicycle worth 5000 dollars, but as a result nobody in the area cycles to the train station, and parking within 5 minutes of the station becomes impossible.A robber traumatizes the family he's robbed, but also forces everyone into an expensive attempt to have more security than their neighbours.A wife beater causes misery for their wife, but also makes it far riskier for people to enter relationships.I know a fraudster who was imprisoned in the USA for 9 years. Once released he betrothed someone in Canada, borrowed a huge sum of money from her brother, and fled to the UK. There he set up a small trading fund and defrauded a Czech company out of millions of euros. He offered to invest his local synagogue's money, then ran off to Manchester. This man has left a trail of misery and destruction behind him, and shows no sign of stopping no matter how many times he's caught.A small number of people are responsible for the vast majority of petty crimes. Someone who has been arrested 3 times is extremely likely to be arrested again.I do not believe in vengeance or justice. I do however believe in fixing problems. And it's clear the only way to fix this problem is to put such people in positions where they cannot do anyone any harm.A sufficiently wealthy society would imprison those people in good conditions for the rest of their life. We are not a sufficiently wealthy society.Imprisoning someone for one year in the USA costs in the order of 100,000 dollars. Scott Alexander estimated that making a real dent in crime rates would require incarcerating a low single digits percentage of the population. Each extra percentage locked up costs the government some 300 billion dollars, 4% of the combined State+Federal budget, and far too high a price to pay to give criminals a marginally positive quality of life.Nor is it a price we are prepared to pay. With prisons full, judges err on the side of letting criminals go free, so police officers don't bother catching them in the first place.A swift death penalty for violent crimes or repeated petty crimes would quickly remove the worst offenders from society. It would save the government billions, and encourage police officers to do their job which is actually the most cost effective way of preventing crime.ObjectionsBut what about mistakes?Firstly, you obviously should not impose the death penalty if it's not at all clear who did the crime. Amanda Knox and possibly even OJ Simpson should probably be incarcerated instead of killed, but these are a tiny percentage of actual cases. In the vast majority of crimes we know exactly who did it, and the trial is just necessary bureaucracy we have to go through.But yes, some innocent people will be killed. Just like some innocent people are killed by police shootings, and numerous innocent people are killed by the US Army, murderers who were let free, and mistaken medical diagnosis. We accept that innocent people die due to our actions all the time, and making a special exception here is an isolated demand for rigour.But the death penalty doesn't prevent crime!There is some debate about whether the threat of the death penalty discourages people from committing a crime. There is no debate that dead people commit fewer crimes, which is the purpose of the death penalty here.Besides those studies are comparing a high chance of life imprisonment Vs a high chance of life imprisonment plus a small chance of maybe being killed 20 years down the line. I am extremely sceptical that when comparing a high chance of being caught and then released a few weeks later with a slap on the wrists Vs being caught and then swiftly executed we wouldn't see large changes in behaviour.But the death penalty isn't cheaper than incarceration!Yes, if you wait 20 years and go through umpteen rounds of court cases to finally elaborately kill a small percentage of the people you originally started the process with it's not going to save you any money. We would obviously have to significantly streamline the process, such that people are executed within 6 months of being caught or so.But executions are frequently bungled.This isn't particularly high on my list of concerns, but there is a reason most suicide victims use a gunshot to the head if they can. It is the simplest, most reliable, and quickest way of killing someone. But it blows brains all over the wall, which makes people feel squeamish.So instead we inject people with a lethal combination of drugs which can take hours to work, if it works at all, often leaving them in agonising pain the whole way. The solution is to just use the gun.But can't people change?Yes, people can change. But we currently have no reliable way to stop shoplifters being shoplifters, or any way to distinguish those shoplifters who are going through a phase from those who will be in and out of prison for their entire lives. And until they change they continue to do society immense damage.However I do hope that the knowledge the next time you get caught shoplifting you will be executed, would filter out those who are just in a phase.But are you really going to execute a single digit percentage of all Americans?This is the one that really gives me pause, picturing the rivers of blood that such a policy calls for.Let's get some numbers here. Roughly 6% of the US population will be incarcerated at any point in their life, which gives us an upper limit. Now many of these won't meet the requirements for the death penalty but a large fraction most certainly will.Of those who do, many wouldn't have committed the crimes in the first place if they knew the death penalty was the probable consequence, and those that would have are likely precisely those with such little self control they are the most dangerous to society. But either way we're probably talking of about 1% of the population. That's a frightening number.But what you're probably not aware of is that 0.8% of the US population ends up dieing due to intentional homicide, and a larger, but impossible to calculate, fraction will experience rape. Removing violent criminals from the population, often before they ever work up to killing or raping someone would drastically cut this down.At that point killing 3 million criminals to save the lives of 2.4 million mostly non-criminals, plus largely eliminate other violent +property crime, seems like it might well be a price worth paying, especially when the sensible alternative is not to let these criminals roam free, but to give them a pretty miserable existence in prison.But what about mental illness?As stated above, I don't care about vengeance or justice. I care about fixing things. If someone committed a seri us crime due to mental disease I have two questions:Is there a reliable way of stopping them committing such crimes in the future?If so, is there a reliable way to make sure it happens?If the answer to either of those is no, then they are not safe to be released into society, and we are not a society wealthy enough to lock every such person up.But won't this encourage criminals to take violent steps to prevent capture?After all, might as well be hung for a cow as a sheep. Yes this is a likely cost of the death penalty. I do not think it comes near to tipping the scales.Discuss