Without decency there is no coexistence
As different as interpretations of decency can be, it always refers to an opposite. It is a fundamental condition of living together and getting along. Our ancestors had already come to this realisation. Most of the Ten Commandments in the Old Testament are rules of decency that regulate life in a community: you should honour your father and mother, you shouldn't kill, commit adultery, lie or covet your neighbour's wife or their belongings. (Actually, it's interesting that there's no ban on women coveting their neighbour's husband.) The majority of these dos and don'ts are incidentally to be found almost word-for-word in the Egyptian Book of the Dead from 1500 BC.
Good and bad grace? A look at the origin of the word "Anstand" (decency/grace): it says in the German Brothers Grimm dictionary that the original meaning or use of the word goes back to early modern times. In the 16th century the "decency of war" meant a ceasefire. "That the war may be brought to peace, or at least decency." And further on we read: "... only since the 18th century has one used "Anstand" for decorum in outward behaviour, speaking of good or bad behaviour."
But what exactly is decency? Sincerity? Yes. Respect? Not always. Loyalty? Depends. A veiled woman? Not for everyone. And who or what determines what is indecent? We are endowed with social instincts from birth. Nobody needs to tell us for us to know that our personal wellbeing and that of a community are connected. We are born with protective instinct and sense of justice and must learn when and how we can utilise it. Bad experiences and a lack of social acceptance can lead to this sensibility being lost. But a sense of justice is an inherent virtue, not a disturbance in the evolutionary system.
Our DNA knows not just egotism, but sociability too. We like being involved, belonging to a team, an alliance, a guild or congregation - and those who don't belong to anything at least feel in on the plot. We need each other. But can belonging to a group mean that I reduce my degree of decency - together with the group, under peer pressure? Quite possibly. But such a group won't be a success for long. Because success depends on the degree of being able to work together.
Decency-free zone? Obsession with justice leads to self-righteousness. And those who tie themselves too tightly to one value system, one moral, lose their vision. Hasn't part of society for a long time being moving in an area free of decency, regulation and taxation? Politics governs at all costs, the economy expands at all costs, the media chases quotas at all costs, wins in sport come at all costs, the churches clutch at their truths at all costs, in art success at all costs is what counts. Is decency endangered? Or is it just the transparency of our time that sharpens our senses for it? I think we're living in a good time - and certainly not in an unjust one in comparison to earlier times. But the status quo is not sacrosanct.
Therefore art may provoke, research may newly fathom our bounds, we may question social conventions. Bunkering down in the present state brings nothing in the long term - other than the air deteriorating. We do ourselves good to keep opening our windows and doors in order to establish new connections, to let in the unprecedented and from time to time to renegotiate what decency means to us.
Book recommendation: The Righteous Mind, Jonathan Haidt