Ignoring every conceivable principle of life as we know it, overgeneralization attempts to apply one type of thinking or interpretation of events to a broad range of people and experiences. The problem, of course, is that no two people, nor any two experiences, are ever exactly alike. In fact, the variations between two things that we group together as alike can be as wide as the Grand Canyon and as varied from each other as a cat is to a parrot. Every time we apply an overgeneralization to a situation, we get things wrong. Sometimes we're only moderately off, but more often than not, our perspectives are warped by a whole freaking lot. The end result is that we interpret a situation incorrectly, often in a way that makes us miserable.
There are several prominent overgeneralizations people routinely engage in:
The Good/Evil Over generalization
One of the most popular overgeneralizations is the tendency for people to group others or their actions as either good or evil. If someone does this and this, they're good. If someone did this or that, they're evil. Not only is this a flawed and over-simplistic approach (the assessment of "good" or "evil" is dependant upon the perspective of a particular person in a particular time and place, and thus varies greatly from person to person and culture to culture) but it backfires on us in numerous ways. In order for someone to be "evil," they must have committed their hurtful acts out of spite and with full knowledge of the negative consequences it would bring. Of course, thinking such a thing only makes us feel worse. It creates unnecessary social pain and stokes our anger, which impedes the recovery process. Furthermore, it blinds people to the actual causes of conflict. I always cringe when I hear people describe Hitler as evil. Not because he didn't commit some atrocious acts, but because it's such a complete scapegoat that blinds us to the root causes of how the holocaust actually took place. The problem of Hitler was not a man who intended to be remembered as "pure evil." I'm sure in his own twisted thinking, Hitler viewed his actions as justifiable and in the best interest of mankind. It is looking into this, not brushing off such atrocities as the product of "evil," that will give us useful insights.
In our own personal holocausts which take place repeatedly throughout our lives, it's easy to trap ourselves in this simplistic overgeneralization. But in doing so, we blind ourselves to the root cause of other people’s actions, as well as our own. We deny ourselves understanding. We bring more conflict to the situation. And we paint the world as a more malicious place than it ultimately is, making ourselves miserable in the process. One of the worst things a parent could ever do for a child who just endured a negative event is to start into explanations about “evil” people who are “mean” and “try to hurt us.” It’s not true, and furthermore, this general thought process will seep into other aspects of their perception.