Schemas are an effective tool for understanding the world. Through the use of schemata, most everyday situations do not require effortful thought -- automatic thought is all that is required. People can quickly organize new perceptions into schemas and act effectively without effort. For example, most people have a stairway schema and can apply it to climb staircases they've never seen before.Schemas provide shortcuts in thinking that allow us to get through the day. Not only on the physical level, as above, but in highly complex and abstract thinking, we rely on the generalizations we have made before. None of us gets up every morning and re-evaluates our entire set of opinions. Do tax cuts increase revenue? Does my mother love me? Is good really better than evil, somehow? Are the people at that church generally resentful? Is milk good for you? It would be a tiring world if we attempted such things even once a year.
No, we plod along day-to-day pretty much believing what we did yesterday. Even those of us who think of ourselves as questioning everything have only a short list of what is up for grabs on any given day. Even if we challenge ourselves ten times more often than the average Penelope, the amount is still small when compared to the whole.
We seldom question things at all unless some troubling bit of data doesn't fit. Even those we usually ignore, so long as they don't seem to have any practical effect. New cups come in, we hang them on the old cuphooks. Only if they don't fit and start crashing to the floor do we tend to question whether there might be something wrong with the hooks themselves.
This is very powerful in political and social ideas, which is why everyone wants you to adopt their particular schemas. Once you have the idea firmly in your head that the conservatives are just out to get Bill Clinton, then reports of anything he does wrong can just be put into that harmless (to Clinton) filing folder. If you believe Clinton regularly lies to protect his own butt, then you will put the same news story into that filing folder and reject his explanations. If you believe there is no God, then nearly all of what you encounter can be easily fit into that schema; if you believe there is One, nearly everything can be easily fit into that.
This is why so much money is spent on advertising, and political consultants, and public relations. Because it works. Even on you. You hate that; I hate that. But it's true.
Sometimes events or ideas are so powerful, or our expectations help us so little, that we are forced to consider other alternatives. But most argument and discussion consists of trying to get people to even consider an alternative explanation. Most of us figure that if we can jam it into the old system somehow, why bother to consider whether it might fit even more nicely in another?
Because you want to get it right, that's why.