Privacy and online social networks: can colorless green ideas sleep furiously?

One definition of privacy is the selective revelation of information about oneself. With billions of people using social media, it's increasingly difficult for users to control what they're disclosing and to whom. Current privacy protection measures block leakages via privacy settings that are syntactic in nature, but existing solutions don't attempt to cover all the entities who might end up receiving the data, ensure the need for or use of the data collected, determine the duration of data retention, or reveal if the data is merged with external information to reveal the user's full identity. The title of the article is from linguist Noam Chomsky, who used it to distinguish between syntax and semantics. Virtually all privacy solutions thus far handle issues relating only to the first hop of the personal data flow from a user. The gap can only be filled by examining the semantics behind the multihop flow of user data over time. This article surveys the state of the art and presents some potential directions in moving from a syntactic approach to a more holistic semantics-based approach.