We punish people to:
Reeducate them (Not in California anyway)
To prevent them from perpetrating more crime
To punish the criminal
To deter others from committing crime
So will punishing a 12 year old prevent crime? I’d guess that whatever drove him to kill at 12 is not going to go away for most of the 12-year-old murderers, so yeah, it’s probably a good bet that the 12-year old will do more; probably more than a 60 year old murderer. If you execute him he won’t. If you put him in prison for a finite time, “Society” won’t have to deal with the criminal for that fixed time. Whether he’ll do more crime or less as a result of that incarceration when he gets out, I can’t even guess.
If you treat him as an adult, do you punish him “More”? Seems to me that punishment is first something that is appreciated most by those close to the victim. My sense is that there are two camps among that crowd. There are those who will be satisfied with nothing less than execution and those who express compassion. Obviously if you are doing it for punishment, then the bloodseekers want the child punished as an adult. The others, not so much. If we believe in punishment, maybe we should ask the loved ones what to do? I think to some degree that happens (at least from watching Law & Order – where I get most of my crime knowledge – they do).
Will punishing children as adults deter others? Punishment isn’t a deterrent in crimes of passion in general, and I imagine it isn’t any different for 12 year olds. I don’t think this example is likely to dissuade other 12 year olds with murder on their minds regardless of the severity of punishment. Murder for gain is different. Capital punishment does deter in these situations. We see this here: gangs recruit underage members who are assigned to commit murders. The underage members expect to be treated as juveniles and not subject to the death penalty. In this case, I think we should treat the child as an adult to deter not just the 12 year old, but also the gang leader.
Before you get all up in my face about my appearing to favor the death penalty for a twelve year old, let me save you typing. I oppose the death penalty for any garden variety criminal because I think that the administration of justice is so poor. Too many innocent people are found guilty. And the Foxconn managers, and the BP managers and the Wall street bankers retire in Aruba.