Rape is rising. How harsh should the law be?
Murder carries 40 years. Choose a rape sentence. These forecasts show only the first offence in 240 high-risk fictional cases.
Your law looks like a winner. Run the decisions.
240 deliberately high-risk fictional situations, not 240 people drawn from the public. First count rapes. Then reveal murders following rape.
You deterred the first crime. Did you protect the victim?
Change the sentence. Watch which of the same 240 high-risk decisions end in no rape, rape alone, or rape followed by murder.
FOR MURDER+0y
Does execution stop murder? Or move it?
Choose a law, then follow the same 240 fictional high-risk cases through three decisions: first murder → another murder → police officer killed.
Will the harshest law stop the first murder—but remove the extra penalty for the next one?
Reveal. What does the next murder cost?
Both experiments expose the same omission: the penalty for a first crime is not the penalty for doing more harm.
Marginal deterrence depends on the extra expected penalty for causing extra harm, not merely the total punishment.