Philosophically speaking, why is murder wrong?

I asked this question with the "spiritually speaking" tag before and got some... well "religious" answers. I want a simple and logical answer so im asking it this way now.
Update: @ Idiot - my address is Hoggwarts School of Witchcraft and Wizardry, Hufflepuff dorm room 24.
Update 2: @ EddieJ - murder is morally wrong
Update 3: @ EddieJ - murder is morally wrong
Update 4: @ CC, Lord of Misrule and Pull my Finger Awesome answers, thanks. If I could give my take on your points - Natural survival instinct drives us to subconciously seek out and create social paradigms that better our chances for survival. Anything that threatens the wellbeing of an individual can threaten the... show more @ CC, Lord of Misrule and Pull my Finger
Awesome answers, thanks. If I could give my take on your points

- Natural survival instinct drives us to subconciously seek out and create social paradigms that better our chances for survival. Anything that threatens the wellbeing of an individual can threaten the wellbeing of their society and if it does it is deemed "wrong".
Update 5: @ idleness. - what you are suggesting is called "culling", i think... not totally on board with that idea cuz it seems like a slippery slope
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