Is Anonymity Even Possible?

Sciblings are discussing the ethics of anonymity all over Scienceblogs.

I want to pose a different question: practically speaking, is anonymity even possible?


1) There is no standard definition for what is anonymous or anonymized. For instance, AOL released a putatively anonymous database of search queries a few years ago, but it was soon discovered that individuals could be identified in it. Google “anonymizes” some user records but the method they use is pretty pathetic.

2) The field of reidentification is growing in sophistication. Professor Latanya Sweeney at Carnegie Mellon has shown that even census records can be reidentified in Uniqueness of Simple Demographics in the U.S. Population:

…87% (216 million of 248 million) of the population in the United States had reported characteristics that likely made them unique based only on {5-digit ZIP, gender, date of birth}. About half of the U.S. population (132 million of 248 million or 53%) are likely to be uniquely identified by only {place, gender, date of birth}, where place is basically the city, town, or municipality in which the person resides. And even at the county level, {county, gender, date of birth} are likely to uniquely identify 18% of the U.S. population. In general, few characteristics are needed to uniquely identify a person.

And look what Arvind Narayanan and Vitaly Shmatikov did to the putatively anonymous Netflix database.

3) The more you blog/comment/etc, the more fragile anonymity becomes. You may incidentally reveal identifying information, directly or indirectly. The shifting context of information may cause you to inadvertently identify yourself from previous posts. And metadata often is available, such as your IP address, which helps individuals hone in on your location, ISP, etc.

4) One little mistake, and you’re anonymity is gone! For instance, this blog requests email addresses for commenters. People frequently enter a pseudonym or “anon” and yet leave what appears to be a real email address! Sometimes users employ a pseudonym in a context where they want to hide their identity, but then use the same pseudonym on another website where their identity is easy to determine. So, anonymity is contingent upon technical sophistication (use of technologies such as TOR), discipline, and attention to detail.

I am not arguing that anonymity is a bad thing. I think anonymity is key for fostering non-instrumental values, such as personhood, exploration of controversial ideas, autonomy, free expression, etc. But, are we being naive in our assertion of this protection? Can we, as bloggers who are frequently posting about our experiences, enjoy a strong level of anonymity (whatever that is)?