- uses projectile motion to launch the ammunition
- destruction of natural landmarks (mountains, rivers, etc)
- destruction of man-made objects (buildings, railroads, etc)
- the killing of humans and other wildlife
Cannons have impacted a wide range of things, even including economics. There is a market for cannons - in the military and just for collectors buying antique cannons. They destroy countries and buildings, which need to be rebuilt, which in turn costs a good amount of money. In one way or the other, all weapons cost something. You pay to buy the weapon, you pay for the destruction it causes. Either you pay for the lives you take with time in jail or your own life or you pay money. Not meaning to sound all depressing or anything, but it's true!
Cannons have also made their mark on history. They have shaped the outcome of battles and the creation of new nations (like in the American Revolution - cannons like Gatling Guns were used heavily in this war). If not for a wide variety of cannons, the outcome of the Civil War could've been different! The world, in my opinion, would probably be a lot different without cannons.
The ethics of cannons, however, is not as rosy as the impact they've made on the world. I don't think that cannons are morally correct - anything that harms another person isn't what I call "right". I don't exactly think that people should go to war - it is a waste of time, money, and life - and cannons are just another thing that eggs war on. Cannons have destroyed and built nations, true, but I don't think what they do is right. Some people may think that cannons and other weapons of mass destruction are doing good in the world by making nations stronger or tearing down weak or corrupted governments. I beg to differ: cannons may help out sometimes, but that doesn't mean that they're right.