Unless Smith is the author, I think you mean "I beg to differ with the author." :>)
Capital punishment's effectiveness as a tool for prevention is really not even an issue.
1. We send a message that the life of the living is cheap if we don't have a death penalty. The price tag on a life should be extremely hight. What different messages are sent about a diamond ring in a storefront window if the price tag says either $25,000 or $125,000? The second price says the ring is more valuable, doesn't it?
2. Absent the court system that leads to a multi-million dollar appeals process, an execution should be far cheaper than a life imprisonment.
Finally, we should not execute anyone without absolute evidence that they are the ones who committed the crime. I'm not arguing here about whether someone has extenuating circumstances that mitigate his crime and make his a "non-capital" offense. I'm talking about the "act of murder" itself.
Not "within a reasonable doubt" but, rather, "absolute certainty" regarding guilt for the actual murder.
I dare not support the notion that people should be executed without proof. But, I am curious about the standard of "absolute certainty." What types of proof would constitute "absolute certainty"? DNA?
As my comment accompanied a quote from the author, I think my post was properly addressed.