The phrase “common-sense” is so ubiquitous that it can barely be called a cliche. People say it often and thoughtlessly as if it’s just obvious what they’re referring to. But often there’s no such thing as common-sense.
In some situations people might be more likely to act in similar ways which they might see as common-sensical, but often, maybe even more often, there is little agreement. What one person thinks is common-sense another thinks is sense and another thinks is uncommon-sense and another thinks is senseless. I’m not saying there’s no such thing as an objectively best way of handling whichever situation – I think there usually is – but I am saying it’s more often nothing which can reasonably be called common-sense.
I suspect the phrase originated in the same context it is still used: when people can’t offer reasons for why they made capricious decisions, so they make out like it was so obvious and rational that it doesn’t need further justification.
When people justify whatever as commonsensical, what they mean is that they can’t justify it. (This is often seen with conservative political solutions.)
