A Common Sense Definition of Common Sense

Common sense is (literally) what can be commonly sensed. Not thought or felt but sensed.  If you and I are both sensing (seeing) a sunrise, that's something that we are commonly sensing (by way of seeing). As for the rest of what we typically consider "common sense" - it's really non-sense, i.e. non-sensible abstractions, not actual things we sense (by way of seeing, touching, hearing, or tasting) but the "thing-less things" we think (i.e. mentally envision, imagine, speculate).

Redefining common sense in terms of the shared sensory experience (as opposed to defining common sense as the shared fund-of-knowledge or shared belief system or shared living wisdom) allows us to downgrade our assumptions about others' mind-ware (others' "operating system") to a minimum.  This kind of un-presumptuous stance can be helpful in minimizing misunderstanding early on in the human encounter. 

Most importantly, this common sense view of common sense that I suggest here offers a sensible (realistically-minimal) expectation about others' common sense.