Measured by your own personal moral standards, when it is justifiable to take the life of another being by execution?
My reply is rambling a bit here, but I think being honest on this subject means it is ok.
There really is no "justification" for taking another life except expediency. Is there really any "principle" actually worth more than a "person"? I don't think so. If there is evil, killing people is going to be pretty high on the list because it is inflicting and causing suffering. It makes any claim that "killing is good" very difficult to defend if you think of good and bad in terms of pleasure and pain.
By definition taking a person's life is outside of the scope of morality as a basis for regulating social relationships. Execution entails "the end" of the relationship, and the "the end" of the source of the morality itself- namely a person. As people are the
source of individual principles, they are the source of judgements of right and wrong. The death of a person means the death of the principle. To kill someone is to go "beyond good and evil" because you've taken the humanity out of the equation (literally). Death is an absolute and there is no absolute standard of right and wrong because all of them are made by humans, who necessarily make imperfect judgements.
All moralities in this area, in so far as they are social constructs are self-negating and I'm very suspicious of beliefs that say otherwise because it hinges on basing a morality on an authority rather than individual conscience. So it is not moral because killing the person kills the principle to "justify" killing them in the first place. Execution is not moral merely necessary. There is no law for the dead, so can there really be a law which justifies killing people? When do the principles of the community take precedence over the life of one of its members?
I would apply the same logic to "another being" in that I have the
power to kill animals as a source of meat in order to eat. I would also accept cannibalism in an extreme survival situation though that is obviously going to be difficult.
The question for me is what are the circumstances where I would depart from a "conventional" morality to sheer, naked power and expediency. From a human relationship to an animal one. I don't know and I'm happy not really finding out. If you forced me to answer I'd say I'd accept execution "if I could live with it" which is very arbitrary and subjective and not really conducive to a reasoned response. It is also extremely dangerous because a psychopath or someone who simply doesn't care but I'd still prefer to recognise how dangerous and subjective such a judgement is over false certainty.
That's not really an answer but I think anyone who is prepared to kill someone will have to do it with the understanding that they could be wrong or else will give that power to kill to an authority that is capable of mistakes and abuse.
Does this standard vary from your religious or spiritual beliefs? If so, how?
yes. I still have something resembling a belief in the sanctity of human life or the "right" to life despite not believing in either god or natural law. This is an area I am very confused and conflicted because there was not any single text or source to clarify the nature of the belief (when I was still a Communist). The experience of being on the same side of the argument as Stalin, Mao, Pol Pot etc, means the "horror" of the question and the nature of that kind of power is something that stays with me. So instead I have a jumble of ideas rather than anything more logically thought out. I suspect that logical arguments become almost irrelevant when you are dealing with life and death questions (because logic is also man-made and partly subjective). I haven't seen anything to suggest otherwise that makes me feel "comfortable" with the idea.