Azrael
circling Airstrip One
I already have, by citing the rise in the English murder rate since we abolished capital punishment. This is far from the whole picture, as crimes that could be murder are often reduced to manslaughter, very possibly to ensure a quicker conviction. Offences of wounding and assault have skyrocketed. It's only the superb efforts of our doctors and nurses that keep the homicide rate from spiralling out of control.I wasn't presenting it as evidence, just correcting the statistical claim.
I've asked you to present evidence. If it's a deterrent you'll be able to show cases where the death penalty was introduced and murder rates went down. Or cases where it was abolished and murder rates went up. Or even cases where increasing the severity of a sentence acts as a deterrent in murder cases.
As far as I know, no such evidence exists. Which is why I'm asking you to produce it.
I'm unaware of any country that, having abolished capital punishment, has reintroduced it with vigour. New York state reintroduced it in 1995 after a 30-year absence, but, you've guessed it, never got around to executing anyone, and the penalty was struck down by the state courts in 2004. Since my support for capital punishment isn't contingent on deterrence (I'm no utilitarian) I suggest England reintroduce it as the mandatory penalty for murder* and give an example to the world.
(* The trial jury should be allowed to grant mercy on a unanimous vote on a case-by-case basis.)

