Why does proportional punishment give offenders a reason not to commit more serious crimes?

Proportional punishment serves as a critical mechanism for discouraging more serious crimes by ensuring that the severity of a penalty corresponds to the gravity of the offense. If all crimes were punished with the same level of severity, there would be no incentive for an offender to choose a lesser offense over a more serious one.1

For example, if the penalty for armed robbery were no more severe than that for larceny, an offender might perceive no additional legal cost to using violence against a victim during a theft. By maintaining a scale of punishments that reflects the harm caused, the legal system creates a rational framework where the potential consequences for escalating criminal behavior are clearly greater, thereby providing a logical reason for offenders to avoid committing more severe acts.1