Why not execute rapists?

Don Boudreaux has an interesting article on the rationale for sentencing rapists and armed robbery less severely than murder. The basic argument is that the reduced sentence "allows" rapist/robbers to commit their crime without incentivizing them to kill their victims. Twenty years in prison is different from execution. If the sentencing is the same, some who are willing to commit the "lesser" crime will go ahead and kill their victims (they are witnesses after all).

Of course there is one issue to address, which is that with lighter sentencing there will be more crimes, just lesser in severity. This has an interesting application to the single sanction policy at the University of Virginia. Basically, if convicted of an honor violation, you get kicked out of school (educational execution). I think few would disagree that there are varying levels of dishonesty. Punishing them all the same incentivizes dishonest students to take their actions to the extreme. This assumes that the chance of getting caught is the same for both common dishonest acts (e.g. unauthorized help on a lightly weighted homework) as more damaging acts (e.g. stealing an exam and sharing it with some classmates).

The single sanction argument is, "dishonesty is dishonesty; we want none of it!" Well, it's here, yes, even at Mr. Jefferson's University. The question is whether we want to trade-off an increase in less damaging honesty violations with decrease in horrendous violations . Or is the biggest damage the loss of the community of trust?