Originally posted by Big D
Pre-judging is a sign of intelligence,
Here's an example: Suppose leaving your workplace you see a full-grown tiger standing outside the door. Most people would endeavor to leave the area in great dispatch. That prediction isn't all that interesting, but the question why is. Is your decision to run based on any detailed information about that particular tiger, or is it based on tiger folklore and how you've seen other tigers behaving? It's probably the latter.
You simply pre-judge that tiger; you stereotype him. If you didn't pre-judge and stereotype that tiger, you'd endeavor to obtain more information, like petting him on the head and doing other friendly things to determine whether he's dangerous. Most people would quickly calculate that the likely cost of an additional unit of information about the tiger exceeds any benefit and wouldn't bother to seek additional information. In other words, all they need to know is he's a tiger.