Privacy may be corrosive and isolating. Knowing less about our neighbours means we do not know who needs a hand. We are more likely to feel threatened and alienated by those we do not know.
There is a broader worry. Privacy has been most important when public knowledge would be harmful. Often that harm has been unjustified. Think of sexual orientation.
When discrimination was likely to follow knowledge that a person was gay, gays had good reason to keep their sexual orientation private.
As we have adopted more sensible views about sexual orientation, privacy has become less important and the resulting openness has been a very good thing: We are all better off in a world in which we don't need privacy about sexual orientation.
There are still many matters, some important, some trivial, that have the same profile as sexual orientation.
Wrongful discrimination and stigmatisation of mental illness gives sufferers good reason to keep their illness secret. But, like sexual orientation, it seems certain we would all be better off if we addressed the discrimination and stigmatisation so that privacy was unnecessary.
More trivially, many people are anxious to keep their income private, and not simply to avoid their responsibilities to the IRD.
In New Zealand, at least, it's common to disapprove of both those who earn too much and too little, and that disapproval gives people reason to keep their income private.
But surely it is a mistake to think someone's income is reason for disapproval. Our moral worth has nothing to do with our material worth, and if enough people began to think that, the value of privacy about income would go the way of privacy about sexual orientation.
Once one begins thinking of privacy this way, as a response to wrongful discrimination and stigmatisation rather than as something valuable in its own right, we see examples everywhere.
Why are we anxious to keep our health information private? (Suppose no one cared whether I had Hep C?) Why are people funny about their age? Suppose we really abandoned the dopey view that it's better to be some ages rather than other others? Would we still want to keep our age secret?
Is privacy valuable only as a means to avoid the harm of wrongful discrimination?
Perhaps not. It's been suggested we use it to mark different relationships: my wife knows almost everything about me, my children just a little less, my friends a bit less, the stranger on the train almost nothing.
The idea is that we use the control we have over access to information about us to create relationships of different levels of intimacy.
Others have argued that privacy allows us to ''try out'' different public personas quietly and safely, behind the scenes, before deciding what to take on the public stage.
Perhaps privacy matters but we should be awake to its costs. We should think carefully about whether we'd all be better off if we cared about it a little less.