Your brain is a machine for jumping to conclusions.
Usually that’s a good thing. Evolution didn’t have time to finish the design for the human brain before we started overloading it with things like writing, agriculture, politics, and Kardashians. So we’ve become a planet full of beta testers, working out the bugs on each other.
In particular, if we had to consciously solve every individual problem we encounter, our brains would quickly deplete our bodies’ supply of glucose. Instead, we get by on stereotypes and other mental shortcuts. A heuristic is “a simple procedure that helps find adequate, though often imperfect, answers to difficult questions.” Heuristics are nature’s way of making sure your head doesn’t explode.
Good judgment comes from learning to recognize when it’s time to make an exception to the practical rules provided by reliable heuristics – when to disregard Strunk & White and use the passive voice, when to speak up rather than keep your mouth shut, when to wake sleeping dogs, when to wear white after Labor Day, etc.
One of the most effective heuristics is Ockham’s razor, the principle that the simplest explanation for a phenomenon is usually correct. Nevertheless, sometimes life is a little too shaggy for Ockham. Or at least my life.
I shop at our neighborhood Fred Meyer often enough that I recognize many of the employees. For example, there’s a young man with a big smile and a bigger thatch of curly dark hair. He often bags my groceries, and is invariably cheerful and polite.
Last month as he was bagging, I sensed something looked wrong. Eventually I realized it was his employee name badge. I'd heard other co-workers use his name before, and even though I didn't remember it, I knew the name wasn’t what was printed on his badge. My brain soothed itself and restored coherence to its model of the world by hypothesizing he must have borrowed someone else’s badge for the day.
Yesterday when I was provisioning for the kids’ fortnightly return, I noticed the nice curly-haired young man bagging groceries at the aisle next to mine. Then I noticed the nice curly-haired young man working the register at the same aisle. Ockham was wrong. It turns out I should have gone with a less simple reason to explain why I’d seen the same guy so often on my grocery runs to Fred Meyer, and wearing multiple name badges: he's actually a pair of extremely identical twins with the same job.