Which purpose of crime is described as exacting equal "pay back"?

The purpose of crime described as exacting equal "pay back" is retribution. This concept is rooted in the idea that when a crime is committed, the offender deserves to suffer a punishment that is proportional to the offense they have inflicted upon the victim or society. Retribution is focused on justice and moral blame, asserting that the wrongdoer must face consequences that balance the act of harm done.

Retribution is not merely about preventing future crimes or compensating victims, but it emphasizes the moral obligation that society has to respond to wrongdoing. This aligns closely with the notion of "an eye for an eye," where the punishment is reflective of the nature of the crime, ensuring that justice is served through appropriate consequences.

In contrast, incapacitation focuses on reducing the ability of the offender to commit further crimes, restitution refers to compensating the victim for their loss, and deterrence aims to discourage criminal behavior through the threat of punishment. Each of these serves different functions within the criminal justice system, but retribution is specifically concerned with the moral imperative of exacting a form of “pay back” for the harm caused.