And the Sudoku puzzle is good for your brain, and hence isn't all that bad for society to the extent that people with healthy logical brains are better than the alternative. Probably true of minecraft as well -- I certainly enjoyed it for a month or three, just as I enjoyed second life more briefly, World of Warcraft in its day, and am currently enjoying the rebirth of Baldur's Gate and Icewind Dale on my tablet. But at some point all of these things -- even Sudoku -- become a form of e-crack, a means of withdrawal from the world, a kind of meditation that replaces the struggle with a dirty scary largely unknowable world with something clean and relaxing.
In the end, it's a matter of ethical balance. If you are working long and hard enough to support yourself, far be it from me to criticize what you do with your elective time outside of that (and vice versa) as long as it isn't things like torturing puppies or crafting kiddy porn. Also, as many have pointed out, one individual probably can't fix all of the ills of the world, and so in a sense it is wasteful of your life to devote all of your elective energy in trying at the expense of all joy and diversion. Still, I think that in between spending all of one's life in a drug or mindcraft-induced haze of complete avoidance of the real world and becoming Mother Teresa there is an ethical optimum, probably quite broad, of doing no particular harm, being as responsible for supporting your own personal life and its self-assumed obligations (like children and pets) as circumstance and ability permits, and yeah, out of sheer self-interest if nothing else spending some of your elective energy on making the world a better place for everyone because that makes it a better, safer place for you yourself. It needn't even be false or religious altruism, in other words, even if your personal ethos is a single life to live, no god, no afterlife, most of us would prefer to live in a world that minimized the personal risk of being burned alive by religious zealots, being beaten or killed by thugs and bullies, starving to death because some accident robbed us of the ability to work for and feed ourselves -- and so in a very deep sense fulfilling a "social obligation" to help others is part of an optimized selfish ethic, a way of buying "insurance" through one's actions insuring others.
So how much Sudoku, or Minecraft, or WoW/BG/IWD or Diablo II Expansion is too much, compared to doing something more constructive with some part of that time? That's the choice of each individual, but I think that it is arguable that if you get to where you are building word processors out of Minecraft you m-i-i-g-h-t be a hair over the line...;-)
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