manners are the social rules of a situation. They are necessary for a society where everyone isn't constantly at each others throats and the amicable resolution of conflict. Without manners and social rules humans wouldn't have been capable of organising even hunter gatherer societies.
some fragments of society have different rules such as the aristocracy. Those rules are only required if you wish to fit in with said aristocracy
manners are the social rules of a situation. They are necessary for a society where everyone isn't constantly at each others throats and the amicable resolution of conflict. Without manners and social rules humans wouldn't have been capable of organising even hunter gatherer societies.
some fragments of society have different rules such as the aristocracy. Those rules are only required if you wish to fit in with said aristocracy
That's a strong claim unless "social rules" is doing all the heavy lifting. What do you mean by manners?
manners is a very broad term it includes how you speak, how you dress, how you confront someone you have an issue with, how you treat guests etc
for example it is bad manners to play loud music late into the night and it is bad manners to threaten violence