There's No Such Thing as Common Sense

I've got a real problem with the phrase "common sense." I guess you'll keep reading if you've got any.

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The phrase “common sense” and its variants should be removed from ones speech altogether. Let me explain.

Think about the context in which the phrase is typically used—when you do something wrong your superior may tell you that you need to “use some common sense.” Or when you ask a question that is perceived as ignorant you might hear the phrase “that’s common sense.”

In its most severe form “common sense” will be used to berate a person, e.g., “That guy has no common sense whatsoever.” It is rare to hear someone being complimented for their common sense.

So at its worst “common sense” is mean and insulting and at its best, it’s just plain condescending.

When I think of “common sense” I think of, “don’t put your hand in a fire.” and “don’t run into a busy street.” But even those aren’t “common.” A two year old would probably do both without thinking twice. That is because he doesn’t know any better—he has not learned what is so common to others, and subsequently has not developed that “sense.”

One may argue that “common sense” is based on age, culture, or profession. But that argument breaks down easily. For example, it may be considered common for a farmer to know that a hen lays eggs without being inseminated by a rooster (those are the kind of eggs you buy at a store). But someone who is not in that profession probably doesn’t realize that fact. A hen will lay eggs regardless, but without a rooster they will not become chicks.

A web developer may know what the term “instantiation” means, but it really depends on the technologies that she works with. Someone who has not studied programming will have no clue what that term means.

It should be clear at this point that “common sense” is merely a set of assumptions a person makes about a topic in which he or she has explicit knowledge. Everyone is different—their experiences and interests dictate their knowledge. It is something we should try to remember when we are tempted to assume that something is “common sense.”