That's just my opinion.

Dear Spacey, here are finally my announced comments to your Batman slaps Robin meme "How would you change people who like hate and violence" (sorry for the delay, but I have to work for my living):
Haters: men and women
people liking hate a n d violence: mostly men.
There are two major groups:
"cold" hater with violence, and
"hot" haters with violence.
"Cold" haters with violence: so-called "psychopaths" (clinical definition: people who lack empathy and compassion). These people can switch off their "mirror neurons" completely (if you are not familiar with "mirror neurons", please google it). Psychopaths and pedophiles are, in my opinion, probably the most dangerous kind of people on this planet.
Suggest for dealing with psychopaths: I once read the report of a psychologist (I believe he was from Harvard) who exposed his brain to a certain strong magnetic field ans was able by this to switch o f f his mirror neurons, he reported that he watched extremely cruel movies in that state of mind and thought it was funny and only laughed. (I would not be surprised if this information could not be retrieved from the Internet any longer - it would not be the first "politically undesired" information that disappeared from the Internet). Psychpathy is very probably conneceted with a high high skin resistance and can so be detected already in babies - they do this in Mauritius, but I don' t know what they do in Mautirius to treat these babies and prevent that they develop psychopathy, that woudl have to be found out. My proposal for grown-up psychpaths (if you don'tz want to wait tilllthey die): if it's possible to switch off mirror neruons by a magenitc field, it should be possible to switch o n mirror switched off neurons by a magnetic field with the opposite polarization as well, and then force those people to see cruel videos (this could be done in a prison - reminds, of course, of "Clockwork Orange") and repeat this as often as necessary so that they really feel what they are doing when they harm other people (they might need accompanying psychotherapy for that, if they couldn't bear it). The trick would be, of course, to keep the mirror neurons switched on. My guess, give them the reward of feeling love (n o t sex!!!) when they have them switched on, and punish the, when they switch them off. At least the phenomen could be studied in detail like that, and if it were not the solution, one could look out for further ideas (is there a deep traumatization

etc.)
"Hot" haters with violence: they are certainly deeply traumatized. I now from myself that when certain traumas (usually from childhood) are triggerd you can get such enormous physcial and emotional pain that you really want to take a gun and go out and shoot people (read the childhood biographies of Stalin and Hitler and you will understand why they became devils - they had enough genius to become devils for millions of people). Of course children and teenagers having this potential should be picked out by routine obligatory psychological test for everybody in schools (it should not be very diffult to find this out) and get psycholgical treatment. Porposal for treatment, even of grown-up people (old Buddhist wisdom, not invented in modern times): 1. make them aware of their deep anger (many suppress it so miuch that they don't even realize it), enough techniques are available for this. 2. Let them spit out their anger in words (e.g. screaming and yelling), fi necessary even in non-harming deeds, like smashing things in special suuroundings. 3. Most important step: make them turn their anger into a c r e a t i v e force. Show them that desctruction does not give good results and let them invent their own ways to turn this powerful emotion into something constructive (ask Buddhists or really good psychologists for further information, I myself have found my own ways, but different people might need different ways, and their is not enough room here to discuss this in detail).
I hope this can give some hints how to solve the problem. I am sure if there really were a sincere effort to handle this in a productive way by non-idiotic skilled persons, it could be done.

Please forgive any typos - I did not proofread (too tired).