What is Privacy?

Scott McNealy once famously said, "You have no privacy. Get over it."

I doubt that even Mr. McNealy believes this. Mr. McNealy would not like it if somebody continually accosted him while he tried to go about his business (what lawyers would call the tort of intrusion). He wouldn't like it if people tapped his phone. He wouldn't like it if somebody tried subvert his relationships by spreading falsehoods (or worse, cunningly chosen truths).

We all cherish our privacy. Unfortunately we're often asked to trade off privacy for some other thing, say money or national security, without really considering what it is we're giving away. The philosophical definitions of privacy I have seen tend to be too complex, miss important elements of the privacy, or both. On the other hand, the simplest definitions don't give much real guidance. Justice Brandeis defined privacy as "the right to be left alone." While this is on the right track, it doesn't really capture the full spectrum of rights.

Privacy is not just about being left alone, but about the right to control our engagements with other people. Who you choose as your friends is clearly a personal matter and interference with this choice is clearly a privacy intrusion.

After considering this for a while, I believe that every privacy concern boils down in some way to the issue of autonomy or self-direction. This is most easily seen when it comes to issues of intrusion. If you are in a public place, you must expect to be seen and observed by others. But if somebody begins to follow you around as you go about your business, they cross the line. They're interfering with your freedom of choice of places to go and things to do.

Autonomy is also behind other privacy concerns, but in less obvious ways. The neighbor who makes loud noises interferes with your autonomy of attention. The person who spreads misleading facts about you interferes with your ability to control your reputation through your own choices. The person who goes through your trash in order to find out about your private habits places curbs upon those habits.

Privacy is not autonomy in the sense of absolute freedom; it is about freedom to make choices in light of reasonable consequences of those choices. Therefore, I would offer this as a definition of privacy:

Privacy is the right of an individual or group to be free from unreasonable interference in the conduct of their affairs or in their thoughts.

I believe this covers every form of privacy concern there is, as well as the normal excpetions and trade offs to privacy. In every case, issues of privacy turn out to be issues of freedom, and exceptions to privacy turn out to be reasonable consequences of our freely chosen actions -- or at least they should be.

I started to think about privacy again after reading some posts by people who were struggling with the question of whether privacy was really needed in a free society. I believe that privacy in fact defines a free society, both in the way it limits intrusions of others in our affairs, and in how it limits our expectations to be free from the consequences of our actions.