When I was a kid, I thought my grandparents were being unfair when they criticized me for lacking common sense. After all, if common sense is something that's learned from life rather than a book or a teacher, then of course older people have more of it than younger folks.

These days, I think I have more common sense, but it's not easily measured — or defined, for that matter. If you look up common sense in various dictionaries, there are a variety of definitions. They all include the idea of "sound judgment," but from there they vary. But doesn't judgment vary among people with different life experiences? I consider driving cross-country solo no big deal — I've done it twice and loved it. But some people told me I was crazy — that it was unsafe for anyone to drive that far without company.

Perhaps that's why Francoise Marie-Arouet, otherwise known by his pen name, Voltaire, is known for saying "common sense isn't so common."

In fact, if you want to try your hand at the lighter side of common sense, check out these questions:

But seriously, can't common sense be dangerous?

Americans in particular seem enamored with the idea of common sense, throwing the words around judgmentally when people do things differently than they do. But perhaps this kind of "common sense" is actually dangerous — and biased. It assumes a common set of experiences, and if there's a country where people with a wide variety of experiences come together to form a union, it's the United States. Not only do people who arrive as immigrants have a variety of past cultural experiences, but people of different ages and races also have varied experiences of the world.

So your common sense is not going to be my common sense. How could it be?

As Jim Taylor writes in Psychology Today, "Perhaps the biggest problem with common sense is that it falls prey to the clear limits of personal experience. Or, we don't even have any actual experience in the matter and rely simply on what we believe to be true or have been told is true, what we might label 'faith-based sense' (in the broadest sense of the word faith)."

Common sense then, seems to be making up a good answer to a situation based on experience you may or may not have. Either way, you're supposed to figure out your dilemma without outside assistance. But what's wrong with researching something, or consulting an expert when you're in a situation you're unfamiliar with? Why should you rely on your ignorance and bluster through when you can get more information?

Maybe real common sense is the kind you crowdsource for — the wisdom of the group, including those more experienced than you. After all, that sense is, by it's very definition, common.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.