This line of reasoning interests me because it seems to arise in other contexts as well.

Do very harsh punishments significantly reduce future occurrences of the offense in question?

I've heard opponents of the death penalty argue that it's generallynot the case. E.g., because often the criminals aren't reasoning in terms that factor in the death penalty.

On the other hand (and perhaps I'm misinformed), I've heard that some countries with death penalties for drug dealers have genuinely fewer problems with drug addiction. Lower, I assume, than the numbers you'd get from simply executing every user.

So I'm curious where the truth lies.