Lately I had a discussion with a friend online where that person told me, essentially, that companies will naturally take advantage of their customers to the extent permitted by law. I promptly disagreed. The recent string of filibusters in the United States Senate is a really good example of how, when people really take advantage of others to the extent that is legally permitted, things go off the rails so far that it becomes time to change the laws. What was stopping minority groups in the Senate from filibustering everything in sight before, when they had the numbers to accomplish it?
Common sense and good manners.
That got me thinking. What makes common sense? How do we dictate manners? When are laws necessary and when are they not necessary?
When groups are really tiny, say a single family tiny, people can negotiate what happens person to person, and express their feelings to one another. There are power dynamics, of course, since a child won't be able to dictate to a parent where the family will go on a certain day if appointments or parental preference say otherwise. But it tends to be negotiated face to face, with little need for rules or voting.
Take that group and make it a little bigger. Maybe it is a small farming community, or a village in the countryside. Everybody there still knows each other, and there are certain understandings about what one does and what one doesn't do. Everybody knows you don't walk across the corner of that cornfield because that particular farmer will get upset, or owns a dog, etc. Community understandings about behavior are formed, and a kind of common sense develops that is appropriate to that context. Nobody needs to write anything down.
Common sense is something that we often invoke, but keep in mind that it is culturally based. Common sense grows within a community out of a sense of shared destiny and needs, and the specifics of it are determined by the nature of the physical and social environment. That means that when a sense of shared destiny and needs is lacking, or the context is not shared, then common sense and manners will fall apart.
That's when laws start to be useful, because they provide a contract that is objectively agreed upon (ideally, though not uniformly!) by the members of the community through a carefully outlined process. Clearly there are disagreements between cultural communities about what kind of laws should exist, too!
When it comes to oppressed populations, that's where things get complicated. Oppressed populations are typically defined as "Other," i.e. as non-members of the greater population. This means that members of the dominant group are less likely to apply common sense rules and manners when dealing with these groups. It also means that since common sense rules and manners are seen to apply first to every situation, and the invocation of laws requires more effort, that unfairness is likely to start right there on the ground. Even when laws are invoked, they are invoked at the peril of the oppressed group. First of all there can be social repercussions, censure and punishments that are administered at the non-legal level. Second, if the laws do not explicitly refer to the oppressed group as possible beneficiaries, it is easy for members of the dominant group to claim that the law does not apply to them. Third, there can simply be bias in the people who are called upon to enforce the law. Even just dealing with bullying is a huge challenge because friction can enter into the process at so many different levels; dealing with large-scale injustices is far worse.
So many of the things we think of as natural and expected behaviors in our own lives are less a product of law than of common sense and manners, and thus we cannot assume that they would be natural and expected behaviors toward anyone who is not considered a member of our own community for one reason or another. People find many reasons to institute exclusions. Privilege has to do with the seemingly reasonable expectation that common sense and manners can always be expected to work in our favor. That evaluation will be fair, advancement will be on the basis of merit, and that laws will be just. However, the definitions of "fair" and "merit" are also culturally based, and subject to either ease or difficulty based on whether they run alongside, or run counter to, our common sense. And common sense is for insiders. A person who can walk into another cultural community and expect every rule of manners and common sense to conform to their own view is engaging in a privileged expectation. This is not how things work. When I go to a foreign country, I don't expect people to follow my rules; however, there are people who do have that expectation when they travel.
I am sharing these thoughts because I feel they apply to real life. That means they also apply to worldbuilding. I hope you can take something from this to help you think through the kinds of interactions that might take place in your fictional worlds as well.