For many years, privacy has been evolving to become a right as fundamental as equal protection or free speech. But what if it comes at too high a cost? What if we have too much privacy when technology now makes sharing information so much easier and the value of shared information so much greater?

This is the thesis of a new book, "Public Parts: How Sharing in the Digital Age Improves the Way We Work and Live," by Jeff Jarvis, a journalism professor at the City University of New York. In contrast to privacy activists, he argues...