I wonder if they were really focusing on the family needing to be punished, vs. the murderer knowing what they've done to their family. In such a case, you could argue that it does not and should not hurt the family any more (or not much).
You don't have to stand by family, and can feel very little different about their receiving justice; perhaps a bit worse, since you don't know what else they could do before being laid to rest.
I thought this was getting dismissed too quickly, but I forgot how directly this was said. Yes, if you literally want to hurt their families, that's just insanity; lashing out at people who had nothing to do with it...
... although there's a really interesting argument that you're always doing this when you punish someone.
It's the intention that matters.
Punishments have several functions -- to work as deterrent, to keep society safe from the perpetrator, to change them so that they won't repeat their crime in the future, to compensate the victims if possible, and also pure retribution, to let people feel "they got what they deserved."
To me, that last one is the least important, and "tooth for a tooth" makes the punisher guilty of the same crime as the perpetrator.
When I said "punishment" I meant the purely revenge version. I was basically working from that assumption, and this is what we'd been previously discussing.
So, I was purely speaking from a harm perspective. The argument is that it makes no sense to try to harm anyone, for any action, no matter how evil.
Without "free will" this is a violent act of senseless aggression against the innocent. Interestingly, if it's an animal we think it probably doesn't have "free will", however we accept this as a reason IN FAVOR of disregarding their rights (eg. the killer bear doesn't think and feel like us, just shoot it).
With modern sensibilities, you shouldn't hurt people unless they do something under their own "free will"; but this is never true, if we don't have "free will" to begin with.
So if an animal kills we use their lack of free will as a reason to kill them, but if a person doesn't have free will, then that's a reason they should be spared; doesn't this just seem like we've created another spiritual concept, to shape based on our cultural values.
P.S. Even arguing the inverse case, it's tempting to use lack of free will as a justification for leniency; at the same time you'll be very quick to use some form of it as a reason in favor of the sanctity of life.