It’s just the way it’s done. It’s common sense. You shake a spray can to get the ingredients distributed before spraying; otherwise, you end up spraying all the propellant and leaving the valuable stuff in the can. You have to shake well before using.
But, one day I actually read the label on a can of Febreeze I was reaching for (we won’t go into the backstory). It was shocking. There in bold face, in all caps, like a PreSidential Tweet, we words that ran counter to common sense:
“FOR BEST RESULTS, DO NOT SHAKE.”
I had shaken that can dozens of times before. You always shake the can! Just not if the can contains Febreeze. Common sense does not apply to Febreeze.
Now, there are people who quip, “Common sense isn’t so common.” I’ve even been known to argue it doesn’t exist at all. But, it does. “Common sense” is usually just a lesson we learned so deeply or so long ago that we don’t remember learning it. We don’t even think about why we believe “it’s just common sense.” It’s a shortcut that keeps us from having to think about our opinions or the actions we’re about to take.
We start out with, “righty-tighty, lefty-loosey.” It’s true so often that we stop thinking about it. We automatically turn the lid to the left on a jelly jar. It’s just common sense. Until we encounter one of those sinister reverse-threaded bolts.
We use common-sense shortcuts every day to speed up our decisions or just to take a little load off our overworked brains. Usually, these shortcuts are harmless or even helpful. But, sometimes they’re not. Sometimes they can be counterproductive or even harmful. Sometimes we need to stop, step back, and take a moment to think about what we’re about to do or for whom we’re about to vote. Does that person really reflect my values or are they just the Right Party?
Sometimes the nut loosens by turning it to the right. Sometimes we shouldn’t shake the can. Sometimes common sense leads us astray.