Everyone has an opinion on Ndamukong Suh's personal foul last Thursday. Should he be suspended and if so, for how long? I'm not sure what the right answer is, but I'll spell out some principles of punishment.
For some reason people think this site is about football statistics, but it's really about articulating the un-articulated. It's about identifying that which flies under the our radar of intuition. When we identify our pre-conceived assumptions, our thinking becomes clearer. While I don't pretend to be a professor of criminal justice, I'll share some thoughts on what punishment is about.
In my mind, punishment has at least five possible purposes: incapacitation, restitution, rehabilitation, deterrent, and prevention of retribution.
While a criminal is behind bars, he cannot harm the rest of society. And while an unruly player is suspended, he is unable to harm other players or embarrass the league on the field.
When a thief steals $200 from a merchant, it makes sense that part of the punishment should include repayment of what was stolen. If a vandal defaces a school building, part of his punishment may be scrubbing the paint from the windows. Often, a crime's harm cannot be repaired directly, and other times, a crime may be against society (or in the NFL's case, an organization) as a whole. In this circumstance, general fines can be levied so that a society or an organization recoups something for the harm done to it.
Although I don't have a lot of faith in this principle, some people believe in rehabilitation, many of whom make a nice living from trying to rehabilitate other people. We don't want the offender to repeat his offense, so the punishment should be strong enough to affect the disposition of the offender enough to prevent repetition. Rehabilitation is one of those things that sound so nice and so plausible but aren't proven. You know what else sounds nice? Fairy tales. Santa Claus. Strong running games. Momentum.
By deterrent, I refer to deterring future offenders, including the perpetrator in question. The punishment should be strong enough so that the expected pain of the sentence is greater than any potential benefit of the crime. The same way we do expected utility computations for fourth down or onside kick decisions, there are expected utility values for all decisions, criminal ones included. Although people don't really think that way, incentives are critically important. They act in the heat of the moment and succumb to short-term and irrational inducements, so punishments have to be asymmetric in their severity. In other words they should be severe enough so that there is never a question as to whether it's actually worth it to commit the offense in question, even in the heat of the moment.
Prevention of retribution
Another purpose of punishment, one that I think we've lost touch with in modern society, is to prevent a cycle of vigilante retribution. The ancient verse eye for an eye, tooth for a tooth is widely understood as recommending retaliation. In tribal societies absent of a central authority, it was common for cycles of retribution to spiral out of control. If one party knocks out another's tooth, pretty soon the victim's cousins would be exacting revenge on the offender's family. I understand the verse to mean hey dummy, don't take an eye in exchange for a tooth. Knock out the other guy's tooth and let that be the end of it. Otherwise we've got the Hatsfields and McCoys, Montagues and Capulets, or Bosnians and Serbs.
Unfortunately, aggrieved parties will naturally tend to perceive their own tooth as more valuable. They'll tend to perceive accidental harm as intentional, and soon enough the cycle of escalating retribution begins. In a violent, emotional sport like football, this is a certainty. The central authority, the League in this case, must short circuit the the retribution cycle by punishing the offenders severely enough so that the victimized parties feel satisfied that justice has been done. In sports we frequently witness cycles of retribution. Pitchers plunking opposing batters or throwing at their head, hockey fights, flying elbows in basketball, and so on. What ultimately breaks cycles of retaliation is when the offenders are sternly punished.
An argument against strong punishment in Suh's case is that it was an emotional and natural reaction in the heat of battle. He may have felt that he was on the receiving end of a cheap shot while bent backwards in a vulnerable situation. But this an argument for severity, not forgiveness. The more 'natural' or 'understandable' the offense is, the more tempting it is to commit and the more likely it is to be expected in the future. To deter it, the punishment must be that much more severe, not less.
As commissioner, Roger Goodell has to take all these purposes into consideration when meting out punishment for flagrant rules violations. As contrite as an offender like Suh may sound, it's not relevant in terms of deterrent to the league as a whole.
It's critical for a violent sport like football to constrain its violence. Sometimes this might mean a punishment that seems more severe than necessary for a particular offender. But severe penalties are sometimes best for the organization as a whole. Players gripe about fines and suspensions, but the truth is every player is better off in a league that confines violence to between the whistles. They're all better off in a league that prevents head injuries and protects vulnerable players. They're all better off in a league without an image of savagery.