Why Civilizations Have Laws

i think that civilizations have laws to keep everyone safe. I thinks its that because if there was not a law that you could not kill someone. then imagine how much the population would go down. Also if there wasn't the law that you can not speed drive. then also imagine how many people would have died from car accidents. But i think that the Hammurabi's laws were a bit to harsh. one because the of the law "if your son hits you, you can cuts off his arm" now i think that is too harsh because the son might have been defending himself. so the farther is the one to blame. also if th farther was harming his son shouldn't the farther have his arm cut off? anyway theHammurabi's laws are too harsh!