Besides what you think, do you have any factual numbers to support the idea that capital punishment deters violent crime?
Even if it did, which I doubt. Haven't we as a society evolved past the idea of an eye for an eye?
Do laws deter crime? What "deters" crime? Crime still ocurs even though we have laws. Any stats that support crime figures when there is no law or punishment? Do people speed less that traffic fines are issued?
The "death penatly doesn't deter crime" argument is weak. By that reasoning even laws and punishment doesn't detercrime. We should all be having snuggly polite worded intervensions over hot coco before a liesurely strole over the the rehab clinic.
The point of capital punishment is not necessarily a deterant. It is partly to remove a habitual / chronic or incorregeable member of society from that society. Banishment is no longer an option. Death is the removal option at no additional expense to the public. I don't have North American figures, but in the Uk it costs $100k / yr to house, feed and detain a prisoner. The average income is less than $50k!!!!
So why again is society footing the bill? Why are we deluded into believing in the humanist myth of rehabilitation? Because we think there is no God to sort them out when they die? Because this is the only chance / life they have, and even the sickest killer shouldn't be stripped of some "right" to life?
Well even in a Godless justice system, the final justice is man made laws, and the laws of a society. We become the ultimate definition of Truth and justice as there is no higher being to ursurp our judgements and understandings. There is no future generation to judge us. There is only us, here and now, dealing with a psycho. We, even as humanists have a right to take another's life, especially when that psycho took the rights of others.
Humans are utter vile creaters with sparks of greatness. Humanism is misplaced to think every human example or specimin is a example of the whole. We can take Darwinian measures into our own hands and "cut the fat".
In a Godly system, well it's sanctioned and God is the ultimate judge who will sort it all out later. Life doesn't end with death, merely the executed is removed from the test that is this world, due to their own complete premature failure, or having caused others to fail through derailing others from their own fair shot at existence on this Earth free from evil and human inflicted misery.
In both systems capital punishment is valid. Only the deluded humanist who thinks any and everything human is sacred will advocate the rights of he who would rob others of their rights.