Greed is a big cause: Governments want money, power, and etc. They have a huge ego that they wish to feed... Another one is straight stupidity. Some of us humans are so stupid that they think killing each other will make the world a better place. It would most definitely help if government wasn't so dang stupid and greedy.
As long as Man lives, war shall prevail.
I sadly agree; there will always be some corrupt being that corrupts the minds of other people.
There will be no peace, ever! I believe in the future, there will be war over land, resources and all that crap. I heard that the United States doubles it's population in 3 months alone. They will need to feed all those people living there or they will all starve to death. So there will be conflict over land for farms and major industries sparking war with other countries. I believe the human race will perish in about 100-200 years.(just my opinion)
This is an example of war from a child's point of view.
Child 1 goes into a playground and finds child 2 on a swing. Child 2 leaves the swing so child 1 takes his place. Child 2 comes back and starts to fight with child 1 because he took his swing. Know imagine child 1 and child 2 two countries, the swing a piece of land and the fight warfare. Know you've got a war scenario.