To a certain degree
Some days I wonder...
Seriously though, I believe common sense is nothing more than the ability through observation to correlate causality.
Some people are phenomenal at it others....eh, not so much...
I believe that most people misinterpret the meaning of the phrase. It's common, just like it says, and it's not necessarily an informed opinion and doesn't necessarily involve rational thought or logic - most of the time it's an emotional response. We don't want to admit that common sense it's rational thought because if we did that, then we would be admitting that we don't think rationally.