We gather information from the outside world through our senses: sight, hearing, smell, touch, and taste.
The term “common sense” originated in the late 14th century, and originally referred to an internal mental power supposed to unite the impressions conveyed by the five physical senses.
Our senses are intentionally limited. This is by design, to keep us safe. For example, dogs can hear a wider range of sounds than humans can.
Everything you know is based on what you’ve taken in through your senses over your lifetime. If you haven’t experienced something, it’s hard to imagine it.
No matter how much we think experience, our understanding of life is like looking through a keyhole — a keyhole shaped by our unique experience. We take in only a sliver of the full picture.
When we interact with others who have life views radically different from ours, it helps to remember that each of us is looking through different keyholes. There is no single expression of Truth.
This also explains why common sense isn’t so common.