I gather many believe privacy is a good thing; that it's erosion is a bad thing. But of what basis do we found such beliefs? Is the foundation biblical, or merely cultural? How might we go about articulating a cross cultural ethic for instance?
I think that is quite important, because many people do not seem to regard privacy as an issue at all. It is simply not up for debate. They say "That's private," and for them that is the end of the discussion.
But as Matt Stone points out, it is an issue. It is debatable, because many people have different ideas about what is private and what is not, and how important privacy is. He asks if this is merely cultural, and I think that for most people it is. We each have our own ideas about what is private, and what is not; about information that we are willing to share with others and information that we do not wish to share. But because we rarely discuss these with other people, there is no common standard, and no shared understanding.
In our family history research we have come across relatives who are suspicious of the whole enterprise. They prefer the past to be forgotten, and rather resent our looking into matters that they think ought to have been buried and forgotten. This sometimes extends to things that one might regard as trivial. For example, when my father-in-law, Keith Greene, died in 1983, we wrote about it in a kind of open letter to friends and family members, and included a brief obituary, as a kind of appreciation for him. Among other things we included what we regarded as an amusing incident. He worked for a shipping firm, Rennies, in Durban, and travelled to Maputo in Mocambique once a month. Relations between apartheid South Africa and newly-independent Mocambique were not cordial, and Mocambique had many shortages, so he usually took a carload of groceries and things like toothpaste for people in the Rennies office in Maputo. On one trip they had two pigeons in a cage, and since the pigeons were livestock, and would have to be smuggled in, they stopped at a lay-by just before the border, and jettisoned the cage. But when they got to the border, they found it was closed for three days. They rushed back to the lay-by to get the cage again, but it was gone, and so they not only had to find a place to keep the pigeons, but also a car-load of frozen food, until the border re-opened.
We thought it was an amusing incident that threw light on life in South Africa, and its relations with Mocambique, but my mother-in-law was furious with us for putting it in the letter. "That's private," she said. End of discussion. She clearly drew the line between what was private and what could be shared with others in a different place from where we did. And we found that that was true of many of that generation.
On the other hand, I did draw the line somewhere. The letters were posted in addressed envelopes, and we intended that they should be read by the intended recipients, though we would not have minded if they had shown it to some of their friends. We did not intend to publish it a newspaper where it could be read by anyone. Nor did we intend that it should be intercepted by the Security Police and read by their functionaries, though we knew that that was a possibility. Since Keith Greene had died, he would not be making any more trips to Mocambique, so it did not matter if they knew that he once smuggled a couple of pigeons across the border.
On the other hand, I've been writing an article about the mentality of the Security Police in South Africa in the apartheid era, based on my own file, and their reports refer frequently to "a sensitive source", and it is clear that this often refers to someone in the post office reading outgoing mail to foreign countries, which was illegal without a court order, but that did not deter the Security Police. Though we took it for granted that mail was intercepted and telephones tapped, we still regarded that as crossing the line, and as an invasion of privacy. So though we drew the line in a different place from my mother-in-law, we still drew the line somewhere, and if we had evidence of it happening today in the new democratic South Africa we would complain, probably to the Human Rights Commission.
A student friend of mine went to teach in the rural village of Postmasburg in the Northern Cape, and once in my travels I turned aside to visit her. She was amazed at the lack of privacy and the propensity for gossip. Everyone in town knew everyone else's business, and the main souces of village gossip were the operators at the (manual) telephone exchange and the doctor's receptionist.
A few years later, when we lived in a similar small town (Melmoth in Zululand) we discovered the same thing, except that an additional vector of gossip was the golf course. Local calls were free in those days, and if people were going out to dinner, they would call the exchange and let them know, and so calls would be put through to their dinner hosts. That was the equivalent of SMS, but considerably less private. And of course the party lines that went to the farms were notorious for people listening in.
So there are different privacy standards for rural areas and cities.
I think the idea of privacy is also very much linked to the modern worldview. The Renaissance, Reformation and Enlightenment encouraged the notion of the individual point of view, and perspective (based on a single viewpoint), and this notion also gave rise to the idea of privacy (see also Notes from underground: The ikon in an age of neo-tribalism).
I can't recall that anyone has defined privacy, or expounded the principles on which it is based, or said how we should decide on the limits. And the Bible records the life of premodern societies, so I very much doubt if they had very much notion of "privacy", so I don't think we will find a "biblical" view of it, or succeed in defining it biblically.