From the spectator's perspective, observing perpetual slavery will have a more lasting impression than capital punishment. Perpetual slavery will also seem more terrible from the vantage of the spectator, than from the criminal himself. Beccaria explains the psychology of the criminal who wishes to return to the state of nature in view of the gross inequity between the rich and the poor. Again, perpetual slavery is the best deterrence against this motivation. Beccaria argues further that the death penalty in fact has bad effects on society by reducing their sensitivity to human suffering.
Potential criminals see it as one more method of perpetuating tyranny.
Although capital punishment is practiced in most countries, it is still an error which in time will become rare. He urges rulers to adopt his stance against capital punishment, and predicts that this will give them a lasting fame as peacemakers.