It sure would be great if the world were a peaceful place in which to live. And while it is something our world leaders and our United Nations should constantly strive towards, unfortunately it is possible but not probable that the world would be at peace without militaries. There is a small number of countries that do not maintain military forces but in general, most countries choose to fund and maintain militaries to protect their countrymen.
Human beings will always inevitably have conflicts and these conflicts are too often solved by violent or military means. Some people believe that when humans’ needs are not met, they become fearful and that then leads to conflict.