This is a very interesting question. Perhaps we will one day understand better what genetic configuration predispose someone to be a violent and/ or ruthless individual. Then, these individuals would have limited to no access to the types of resources that allow the production of arms. But what about the normal person? Couldn't the average person be capable of earth-shattering mayhem? What then? Treating how people use things for malice seems to be treating a symptom rather than the disorder. We ought to encourage rational and beneficial belief systems and discourage harmful ones, that is those that should be discarded. Suppose there is resistance. How does one fight a war of beliefs and emerge the victor? Won't we always leave a residue until everyone decides for themselves to discard their beliefs on their own? Such governing must not resort to compulsion, but instead, to guidance and leading the world societies by example. What do you think?
I would love to think that we are capable of eliminating mental illness in adults, or at least diagnosing it early enough so that the harm that individual is capable of is limited, but that's the problem with true sociopaths, they fit in, can pass the tests and are completely unsuspected of wrongdoing until they make a mistake and get caught. And even if we do eliminate the 'threat' of mental illness, what about clinically 'sane' people who seek the mass destruction of others for some personal or political goal? Personally, I hope that by the time nuclear-scale energy densities and home bio-printers become prolific we are spread out enough as a species (Hopefully off planet, and even more hopefully on our way out of the solar system) that one lunatic can't kill more than small percentages of populations. A possible far future that I see is one where you live in physical proximity only to your immediate family and possibly friends, with most interaction beyond those groups occuring in cyberspace. The hope being that we colonize enough heavenly bodies to give everyone their own refuge in the middle of large tracts of wilderness, with cross-planet and interplanetary travel being as simple and commonplace as automotive commuting. That being said, I fear we are heading more towards a "The Moon is a Harsh Mistress" or "The Forever War" type of future rather than a late stage "I, Robot" kind.