You live in a society where everybody steals. Do you choose to steal? The probability that you will be caught is low, because the police are very busy chasing other thieves, and, even if you do get caught, the chances of your being punished severely for a crime that is so common are low. Therefore, you too steal. By contrast, if you live in a society where theft is rare, the chances of your being caught and punished are high, you choose not to steal.
This observation by Italian IMF economist Paolo Mauro in his March 1998 article in Finance and Development explains in broad terms how lawlessness naturally flows from systemic corruption.