Pragma, you're falling into a trap by accepting a false social convention as the definition of common sense.

What people have often referred to as "common sense" isn't.

What they are trying to do is rationalize their unquestioned assumptions by calling them common sense: "Why, son, everbody knows that two men datin' just ain't right!"

(Or, 50 years ago, "Why, girl, everbody knows that datin' a n***** just ain't right!")

Such folks are trying to pawn a cubic zirconium as a diamond.

Common sense, itself, is "good sense and sound judgment in practical matters; a sane and realistic attitude to real world situations and problems."

Nothing wrong with that.

Only when people stop preaching common sense and start using it will social turmoil begin to ease off.

Frank

Good point hyperiongal.

  I've experienced the same wondering about "morals" in another group when someone was trying to start a conversation about what is moral." Morals"  can be interpreted so differently among individuals, just as we see with what is perceived is "common sense."

Another illusion? 

"I know sense, plain sense, horse sense, common sense, are used interchangeably currently, but I'm trying to refer to a more literal meaning for "common sense". A meaning no longer common."

such as....? something not so common, as in a bit more pedantic? real? allogamous, maybe?