"Use Your Common Sense"

I've heard it thousands of times. People use it like a prayer, hoping to ward off stupidity, as if repeating it would bring about enlightenment: "Use your common sense." But what does this really mean? Let's take a look.

Use: it's a command. It commands somebody to execute an action, in this case, to make use of common sense.
Your: refers to the common sense that belongs to the person the speaker is talking to ("you").
Common: refers to something that is shared, not-noble, not special, that happens regularly.
Sense: refers to the ability to perceive something, physically or mentally, or what is mentally perceived using such ability.

Having these words in mind, let's re-construct (or deconstruct) the meaning of the phrase. It seems the speaker is commanding the hearer to make use of an ability they both share, that is not special, belongs to commoners or that happens regularly.

It can be inferred that the action (use) does not happen regularly, because it has not happened. It could also be said that it is probably special, since the speaker has it and the hearer doesn't. The speaker probably doesn't refer to an ability commoners have because it seems as if this ability was a good thing, and seldom does one refer to oneself as a commoner---unless one is running for political office in the United States. And it is obviously not shared, since what the speaker seems to understand clearly is beyond the grasp of the hearer at that point in time. We must accept, then, that this sense, called "common sense," is not really common.

The use of the word "your" along with "common" does not make sense. If it were common, it would be ours, not yours.

Gramatically, the sentence seems to be flawed, but language doesn't necessarily depend on grammar. It depends on people, the context and the way people use it.

When the speaker commands the recipient to make use of his sense, he is really telling him to make use of a sense that belongs to the speaker---probably some sort of specific Weltanschaung (world-view). By adding the word "your" to the sentence, the speaker implies that this Weltanschaung is already part of the hearer, or that it should be. Moreover, because this sentence is generally used in exasperation, it implies that whoever is listening should see the world the way the speaker sees it.

Conclusion: when someone tells you to "use your common sense," they are telling you to see the world the way they do, and that if you don't you're lacking sense.