Murder is unlawful because of societal reasons. It's not technically wrong. We sanction it in the death penalty. We kill others in self defense. We kill our enemies in war. But society judges that to be fine. Religious people used to kill others in the name of religion.
America is a society that embraces freedom and it should include the freedom over your own body and the right to abort. In the end society and the majority decide what is right and wrong.
I would argue the same is true for abortion. Except we can't prove its sentient. So it had even less societal or "moral" impacts. The minority want to ban it. Society wants to do it. Thus it should be allowed. Especially with America's society and its constitution.
If we can't agree on the science, cause clearly that is going to go no where. We agree that religion is not involved. Then maybe we can agree on this.
"Murder" and "killing" (or more technically "homicide") are NOT SYNONYMS.
Murder requires the actor to form
intent to end a life without justification.
Killing someone in self defense, as a capital punishment, or even accidentally, is not murder.
Capital punishment exists to protect everyone who isn't murdering without good justification from those who do. Some argue that life in prison is cruel and inhumane, so putting murderers to death may be seen as less cruel.
If I'm being threatened with severe bodily injury or death, I have a natural right to defend my life and STOP THE THREAT with a reasonable amount of force. If that force I deem necessary at the time includes lethal force, then the CHANCE I MIGHT kill the attacker is real, but not guaranteed. Now, if I stop the threat, and I walk over to the unconscious attacker putting a round in his head, then that would be murder. The killing was no longer necessary to survive.
Once again, you keep falling back to arguing against religion -- something NOBODY ELSE HERE is bringing up. Morality exists in a basic sense even without "society." People with a realization of what life is and what it means to them will employ EMPATHY for other living creatures. Parents instill these values and understandings in their children even without a society and book of laws.
The Ten Commandments didn't need to exist for people to know what was wrong above all other wrongs. Stealing, murder, taking another's wife, lying, and so on all stem from the soon-to-follow Golden Rule. That one rule is based on the concept of empathy: Do unto others as you'd have them do unto you.
Common sense -- not religion, and not "society". Even wild animals don't kill and eat their own without reason that's driven by instinct. Protecting their young, protecting a territory, defending against predators -- and not all of it requires killing to succeed. There's also a food chain, which is a totally separate concept. We're talking about within a species, e.g. Humans.
If you think the only thing keeping you from murdering another person who isn't a threat to you is "society" or "the legal system", then you'd be what's called a sociopath or psychopath. On thing all sociopaths lack is empathy as far as researchers have been able to determine. That's why most of them start out at an early age hurting/killing small animals and pets. They lack the empathy to imagine what they are doing would be like if done to them.
So, stop with the lectures on "murder is only wrong if somebody
decides it's wrong." Humans have intelligence and emotions that guide us when there is nothing else to do so. I suspect you belive the concepts of right and wrong never existed before religion and government. Could not be further from reality.
Do you realize that in most cases, we expend more time, money and resources to make sure we are correct in our death sentences through appeals and reviews -- usually taking years -- to ensure we are not making a mistake than it costs to house them for life? If only we spent as much time, money and resources ensuring we aren't murdering unborn babies who did nothing "wrong."