I believe that the army should exist because if one country got rid of there army and the rest of the countries didn't follow that one place would be the 1 ugly duckling and could be invaded and destroyed at any time but also as we all know not every country would give up their military anyway.
Funds used to promote the military can be utilized for research and advancement of science. Not only that but we could use them for education, healthcare, infrastructure, and public attractions such as museums. This makes us think, should we perpetuate violence for who only the rich benefit? War destroys humanity.
Having an army is an easy way to hurt others and take what you want without money. This is what any army was disigned for, and any protective forces were disigned to fight off such armies. But without a threat we don't need a protection and if every army in the world just drops their weapons, countless lives would be improved in an instant. But we can't do that. Instead what we can do, is improve ourselves and our own children, show them another way, teach them better and then in few generations there wouldn't be need for an army. No one would want to hurt another being unless he's a phycho. Still it wouldn't be a perfect world but it would be a lot and i mean a lot better than what we have right now. No we do not need armies.