Every day, people readily give up information about their buying habits, check in at locations via Foursquare, and post events—both notable and insignificant—online with video or in 140 characters.

Personal privacy is fluid in other ways, as well. Women who wear a hijab or niqab, traditional Muslim garments that cover the head and face, may be asked to remove them for driver’s license photos. People who give to charity can have their names and donation amounts made public. And walking down the street on some college campuses assures people they are being filmed and watched on camera.

To borrow a phrase from Facebook, our modern relationship with privacy can be summed up in the following way: It’s complicated.

Anita Allen, professor of law and professor of philosophy at Penn Law School, says we should care deeply about the diminishing value of privacy in the United States.

“I wanted to write a book about why we should care about the so-called ‘death of privacy’ and whether or not we should have legal and moral interventions to save privacy or to … put some sandbags on the shore to keep the erosion from being too severe,” says Allen.

The result is her most recent book, “Unpopular Privacy,” in which she makes the case that privacy is a fundamental foundational good much like liberty and equality, and people should be protected from giving up too much of it—whether they want these protections or not.

“I think the book is aiming at asking people to think about privacy in a different way,” Allen explains, “something [that] we shouldn’t do without—and we shouldn’t do without it even if we don’t understand that we shouldn’t do without it. People often don’t understand the value of their liberty. We don’t let people sell themselves into slavery. We shouldn’t let people give up all their privacy.”

Allen describes this as “modest paternalism,” the idea that there ought to be some laws that impose privacy on people who haven’t demanded it, or who may not even want it.

Take, for example, the Children’s Online Privacy Protection Act (COPPA), which came into effect in 2000. This privacy law, which applies to the online collection of personal information of people under 13, is a key example of “unpopular privacy.” Neither young people nor website operators clamored for this law, says Allen, “but yet, the United States adopted [it] and put [it] into effect to paternalistically protect children from harm.”

With the exception of COPPA, there are few laws dedicated to paternalistically imposing privacy. But as a society, Allen says we are comfortable and familiar with confidentiality as an area of privacy policy.  For example, people tend to like the fact that doctors, lawyers, accountants, and government employees, among others, are required to keep information confidential.

“We like those rules, and we like them because we understand that kind of imposed privacy—when you force people to keep secrets because they have relationships of trust,” says Allen. “I use that comfortable area of privacy law to help open up peoples’ minds to the possibility that there might be other kinds of privacy duties.”

It’s a fact, Allen says, that this country already restricts freedom in privacy-related contexts all the time—from modesty and anti-nudity laws to laws that ban insider trading and mandate confidentiality.

Privacy laws first surfaced in the late 19th century, when lawyers Louis Brandeis and Samuel Warren wrote the historic article, “The Right to Privacy,” for the Harvard Law Review, attacking the new technologies of instantaneous photography and the mass printing of newspapers. Later, as a Supreme Court justice, Brandeis wrote a famous dissent in the case of Olmstead v. United States, in which he argued that people should have a right of privacy against the police wiretapping without a search warrant.

“[The issue of privacy today is] not, to me, conceptually different than what we talked about in the late 19th century. It’s just the extent to which we can be monitored and surveilled. [The extent to] which we can give up information about ourselves has become very different and much more extreme,” says Allen. “In the 19th century, it was assumed that the average person wouldn’t want to give up privacy, whereas now, the average person is quite willing to give up privacy for a social life, easy access to shopping, and being able to work at home.”

Allen says her book is a philosophical call-to-action, and she hopes that new laws before Congress in the years ahead will provide more privacy protection than people demand.

“I want people to think about privacy as a moral obligation of their own,” Allen says. “It’s an ethical duty, like being honest, like not lying. Not being careless with your privacy is one of the obligations that people have and I want people to think about it that way.”