I'm going to quote someone way smarter than me.
"I will utilitze my mighty powers of stipulation, thusly: the earth is invaded by a race of super-intelligent, but malevolent beings. They subscribe to a xenocidal religion under which they have ravaged the galaxy, exterminating all life when they find it. In the last million years or so, however, they’ve had some sort of reformation, and are now content with a single sacrifice. For occult alien reasons involving astrology, you alone can satisfactorily perform this sacrifice. So, you are given a choice: you can torture one child to death, or the aliens will exterminate all life on earth, over a painful period of time, and wrap the whole thing up by nudging the earth from its orbit into a death spiral terminating in the heart of the sun. Because of your unique religious status, even if you choose not to perform the sacrifice, you will still be forced to kill children, around the clock, in awful ways, for the rest of your artificially extended life. The aliens will keep enough humans alive to serve this terrible purpose, and they will turn a mind-controlling ray on you, under the influence of which your body will commit these acts as your rebellious consciousness looks on in horror. If you agree to perform the sacrifice, by contrast, the earth will be spared, and we will get lots of alien technology which we can use to solve all problems of illness and material want for all humankind. It’s up to you."
Humans. They are the ones responsible for a WIDE number of natural catastrophes, such as oil spills, deforestation, over huntig/fishing animals to extinction, etc. The reason why people pose such a heavy burdon on the natural world is because they eliminated the threat of predators. They eliminated the threat of winter famine. Since little in the natural world aside from natural disasters can control the human population, it has grown unfathomably large, with 6 billion strong and counting. Without natural predators or a good winter's famine to control human populations, what else other than a mass murderer can control it before the natural world snaps beneath their feet, and everyone suffers. Mass murderers can be viewed as those long forgotten predators, long lost in the transcripts of time. Think about it.
Murder is the unlawful premeditated killing of one human being by another. For me, the key word is "unlawful." If you are the citizen of a corrupt, evil society and you take up arms in rebellion against that society, your actions will certainly be considered unlawful. If this includes killing the soldiers of this hypothetical, evil society against which you are engaged in civil war, you may well be charged with murder. Or let us suppose that you are a Nazi guard at one of the death camps during World War II and you decide that you can no longer allow the genocide to continue so you turn your weapon on your fellow guards, trying to stop them, but they are persistent and finally, you start shooting. In the chaotic, bloody battle that follows, you are injured several times, but manage to kill your fellow soldiers. If you survive and the Nazi regime remains in power, you will certainly be charged with murder along with other crimes such as high treason.
Absent such extraordinary scenarios, if we want to define mass murder as the unlawful killing of innocent people in a wrongful manner, then I would gladly say, "No."
No murder can ever be justified. Be it cain who commited the very frist murder on earth by killing his brother abel or anyoneelse. I do believe that no murder let alone mass murders can ever be justified. I can't believe so many of you guys supported the motion. Oh my god.
Murder: the crime of unlawfully killing a person especially with malice aforethought.
This definition clearly implies that murder is killing someone without justification, in this case, legal justification. By definition, murder can not be justified yet people justify it every day. Thing is, people don't always agree with the law. That means that murder is subjective. What one person sees as murder, another person would see as a justified killing.
Humans, being omnivorous, are natural born killers. Our bodies naturally crave animal flesh as well as plants. Thing is, some deny themselves of this. They claim that eating animals or using their flesh (fur or leather) is murder.
Funny thing is, even a confessed killer would have believed they had justification at the time of the killings. This justification would be their motive and without it they would not have killed. Though the rest of the world may not agree, at the time, they believed he had a just reason to kill so to them, it was not murder.