Common sense is impossible to define exactly, but it is more common than you suspect, and less common than you’d like it to be.
Common sense is a Catholic idea. It is based on the belief that God is stronger than the devil, and that His Grace is superior in effect than the devil’s mere pomps and snares.
That is to say: the majority of free moral agents (that’s us) are subconsciously morally correct (most of the time) in our daily moral choices, thanks to God’s Grace.
Here are two common sense concepts:
1) Solidarity – ALL human beings ARE brothers and sisters, even sinners and Saints, dead and alive, now and then and to come.
2) Subsidiarity – all power of one human over another must subsist at the lowest possible level in society in order to preempt the abuse of power, which happens so easily otherwise.