I believe that even complex underlying psychological and sociological issues can be circumvented by directly addressing such most fundamental knowledge. As for deterrence, I believe that the retributive system can in itself serve as a future deterrent, even if it does not do so intentionally. As mentioned, Kant held that any criminal activity is not only a crime against society, but a crime against the criminal him- or herself, since the criminal will suffer for these crimes, even as the victims of the crimes have suffered. Hence, there are no beneficiaries in the system and he deterrent is the threat of punishment itself.

As for rehabilitation programs, these have been notoriously ineffective, regardless of millions upon billions of dollars spent on the research and implementation involved. Even research into the underlying issues surrounding criminal activity has not served to very effectively lower recidivism rates. Hence, the argument for rehabilitation makes little sense to me, because I has proven to be so ineffective. Furthermore, taxes would be far more effectively spent implementing a simple system of crime and punishment that is understood by even the youngest of human beings.

Regarding the arbitrary nature...

Surely the decision to punish and the nature of punishment, should not be easily decided matters. So, although it is simple in general, the system acquires some complexity in this case. Matters of punishment can take a long time to discuss and decide, and rightly so. To mitigate the arbitrary nature of the punishment system, several legislators, interest groups, and votes should be involved. Hence, the desire for complexity among my opponents is satisfied, while my own desire for simplicity is also acknowledged.
In conclusion, the simple general nature of the retributive system appears to be an appropriate way to respond to criminal activity today, since it addresses the basic principles upon which society and many philosophies are built. Society and its well-being are built upon a system of laws that must be obeyed. Punishing disobedience will serve justice while also serving the deterrence requirement of the opposition. While rehabilitation programs tend to be both complex and ineffective, adhering to the complexity requirement of punishment decisions satisfies both opposition and proponent requirements.

These conclusions lead to the final outcome, which holds that Kant's system of retribution, in which a criminal is harmed as a result of bringing harm to the victims of his or her crimes is an appropriate way to respond to criminal activities in today's world.