The Classical Theory of criminology suggests that people choose to commit crimes based on rational calculations of the potential benefits and risks. However, there are three main deterrents to this theory: certainty, severity, and celerity.
Certainty refers to the likelihood that a person will be caught and punished for a crime. If the chances of being caught are low, then even severe punishments may not be enough to deter someone from committing a crime.
Severity refers to the harshness of the punishment for a crime. While some people may be deterred by the threat of severe punishment, others may not be.
Celerity refers to the swiftness with which a punishment is delivered. If there is a long delay between the commission of a crime and the delivery of punishment, then the deterrent effect of the punishment may be diminished.