Common Sense

My dad has a saying, I'm not sure where he got it, but he says, "Common sense, it just isn't common enough."
I have been thinking about this saying or words "common sense" lately. Blake has been sharing with me how people have told him that to have "common sense" is unbiblical. Now, I tend to not give humans a lot of credit. I tend to think we are a stunted people, but is it not logical that God gave us our brain and although "common sense" isn't common enough we should know to use the brain we were given?
This leads me to my last question, why does everything have to be proven in the Bible? I mean isn't it enough that God gave us the bible to show us His character, His overall heart for us and others. Why is it in the grey matter of what is not written we have to "read between" the lines and put something there that was never there in the first place? To me that would mean we need to use some "common sense", well I guess my dad was right again! ;)