Social control is the mechanism society uses to maintain the order necessary for its continuation. Society doesn't like to change; it formed the way it did for a reason, and it has evolved means with which to ensure its continued existence.
There are two basic types of social control. The first is internal control, in which a person is indoctrinated in the values of his society and left to control himself. The second is external control, in which an outside entity (usually an authority figure) provides incentives or deterrents to bring about the desired behaviors in a person.
Internal control is the first defense of society, and often the most effective. Consider, for example, two men who have a grievous disagreement. Will they resort to murder to win their argument? It's unlikely, as evidenced by the fact that many people have such disagreements while few people are murderers. But might we say that this is because of the penalty for murder imposed by the government? To consider this, let us suppose that the two men are spirited away to a far off land, devoid of other people, of law, and of punishment. What will become of them? Will one choose to take the life of the other, will they find a way to settle their dispute, or will they go their separate ways?
Of course, we cannot know the answer for any given man; I can, though, find the answer if I am one of the men in question. If it were me in that far-off land, how would I conduct myself? Would I bow to a law within in the lack of a law without? I would indeed. And since I am, I suppose, an average member of this thing called society, I may then suppose that the average man would do likewise. And so I may conclude that the law that controls the average man from within is more powerful than that which controls him from without.
I have been taught, as have others, to conduct myself in an orderly manner and to treat my fellows as I would wish to be treated. While, in my case and in that of many others, that conviction is of a religious sort, this is not the case with everyone. The urge to control ourselves is as much a practical urge as it is a religious one. We have found that, by co-existing peacefully, we lead better lives than if we did not. Furthermore, we may conduct our affairs without constantly guarding against the malice of others because we may assume that others abide by the same rules that we do.
The manifestations of internal control are two-fold. First, it appears as the action of a conscience, that part of our mind which tells us what we do not wish to hear. When I go to act as I wish, my conscience steps in and reminds me to act as I ought. Second, it appears as the fear of rejection from society. I also act as I ought for fear that I may displease others and so forsake the social bonds I have formed with them if I act as I wish. These two things allow me to control myself unconsciously.
But if internal social control is so effective, why do we need to resort to external control? We often speak of deviants, or criminals, who forsake the values of society to the detriment of others. External control can be both the punishment of the anti-social and the reward of the social. A parent who spanks his child for wrong-doing exhibits external social control, as does one who gives him a cookie for doing what is right. From an early age, this sort of control instills in us a sense that doing what we ought will lead us to pleasure and that doing as we wish will lead us to pain. External control thus results in our ability to control ourselves.
But the very existence of government tells us that the external control of our parents does not always result in people who can govern their own actions. Perhaps it is the result of improper parenting. Perhaps it is the result of a particularly willful or unsociable mind. Whatever the case, some people do not internalize the control exhibited by their parents and become social outcasts. Those who do so in a way not physically harmful to others are considered simply deviant, while those others are considered criminal. At times the lines are blurred depending on how the society views harm. In any case, society then takes it upon itself to correct the slight through sanctions whether physical or social. Perhaps it is incarceration or a fine. Perhaps it is the refusal of others to socialize with the outcast. Whatever the case, society ensures that it will not tolerate the behavior of the outcast until he internalizes the external control that society provides.
So what are we to make of all of this, and how are we to apply it to the game? There are many applications of the concept which we will begin discussing in later posts. For now, however, let's consider social control in the case of gender roles.
Gender roles persist because society has instituted social controls to enforce the order that maintained its existence for so long. There are internal controls in the form of values (e.g., "a woman's place is in the home") and deterrents (e.g., "what will people think of me if I don't marry?"). There are also external controls in the form of societal pressures (e.g., women who buck the social order are looked down upon), incentives (e.g., praise for "the virtuous woman"), and laws (e.g., women are not allowed to vote, own property, etc.). Even if the laws were to be changed, the internal values get passed on for generations, meaning a society based on ensuring the safety and domestication of women will remain the same de facto if not de jure.
Lore snippet: Nerathul society developed in the wastes of the eastern Plain. The need for strong leaders resulted in a paternalistic society. The treatment of women varied across the vast lands of the Nerathim, but classical Nerathul society emphasizes respect for parents of both genders. In that societal model, motherhood and fatherhood are regarded with equal reverence. Thus, each woman is expected by society to strive to bear children. A woman who does bear children is accorded legal status and, unlike in Adunay, may own property. An unmarried woman or one with no children, however, is considered worthless and a shame to her husband. Of course, a woman who has children and abandons them to seek a career breaks the code of parenthood, so the opportunities for women in Nerath are still limited.
Conclusion
Social control, as the mechanism by which society maintains itself, should have a prominent role in any realistic gameworld. Consider what sorts of internal and external control are present in your world, both for NPCs and for PCs, in order to make the society function. Doing this will go a long way towards helping you understand the psychology of your society.