Privacy may be one of the biggest casualties of the Digital Age. If it's not the government that's storing records of cellphone calls, it's advertisers tracking our every online clicks. While limiting government and corporate snooping is now a matter of heated debate, the notion of guarding intellectual privacy has yet to generate much fuss.

Yet, according to Neil Richards, this basic American value to "read and think freely without surveillance" is in peril. Without it, he said, we'll become less willing to test new ideas, challenge common assumptions, and engage in rigorous debate. I recently spoke to Mr. Richards, a professor of law at Washington University, about his new book, "Intellectual Privacy: Rethinking Civil Liberties in the Digital Age."

Edited excerpts follow.

Selinger: Is intellectual privacy something special that’s only for intellectuals?

Richards: No, intellectual privacy is for anyone with an intellect – which is to say, it’s for everyone. Intellectual privacy is about needing to have protections from being watched and interfered with when we’re making up our minds about the world – when we’re reading, surfing the Web, talking on the phone, and sending e-mail to confidants. It's a way of understanding why people get so annoyed when the government and companies monitor our lives, and it was perhaps the greatest interest threatened by the surveillance Edward Snowden leaked. Although intellectual privacy is incredibly important, the right hasn't been well understood. We didn’t have to think about our beliefs, desires, and fantasies as matters of intellectual privacy until recently when we started interacting over digital devices that keep long and detailed records of our thoughts and reading habits.

Selinger: What makes intellectual privacy so important?

Richards: A free society needs citizens with free minds. But as the social science shows, we act differently when we’re watched. We become boring, inoffensive, and mainstream. And this is true of our thoughts and beliefs as well as our actions. When we know we’re being monitored, we might not click on a controversial link or discuss controversial views on politics or sexuality over the phone.

Selinger: Do you think intellectual privacy is currently being threatened?

Richards: Yes, companies and the government have so much control over our intimate information that people live in a state of perpetual uncertainty and sometimes fear.

Selinger: What’s an example of us having less intellectual privacy than we deserve?

Richards: The NSA’s assertion that it needs records of all telephone calls. I bet it would like to have the content of those calls and e-mail, too. The government has lost sight of the fact that free thought and expression are the most important values for democracy to preserve.

Selinger: Beyond government surveillance, is anything else undermining intellectual privacy?

Richards: Yes, corporations are. A few years ago Facebook offered “social reading” and automatically shared things we clicked on and read with our friends. People ended up accidentally disclosing embarrassing things. Amongst all the shame, the trend died a secret and unheralded death. But while this obvious case of intellectual privacy infringement is behind us, we’re still stuck with the fuel that keeps Facebook and so many other companies going: Internet advertising.

Without any public debate, we’ve allowed a vast ecosystem of companies to increasingly profile and segment all of us into our reading habits and interests. We never had a discussion about whether the price of using the Internet should be widespread surveillance. If we could have had this debate early on about giving up access to our political beliefs and sexual activity, I’m sure we would have rejected the deal on those terms. We can have the Internet without surveillance of our minds, and we should insist on that now.

Selinger: Does this view of intellectual privacy justify placing new restrictions on data brokers?

Richards: Yes, we should have a federal Do Not Track law. People have a right not to be profiled when going online, and a legally enforced Do Not Track would make the Internet better – more secure and trustworthy. We should also treat records of reading, thinking, and communications with special, legally protected care.

Selinger: What about new modes of reading? Should an appreciation for intellectual privacy lead us to think differently about devices like Amazon’s Kindle?

Richards: In the past, it was easy to ensure nobody knew what we read, how we read, and even if we read. Now by default the Kindle keeps detailed records of what we buy, browse, how long our mouse rests over a word and our eyes linger over a page, what pages we underline and what the most underlined pages are, whether we finish a book, whether we re-read a book, and what passages we re-read. Some of this data serves useful functions for readers. But it also creates a detailed portrait of Kindle users as readers that, hypothetically, could be disclosed or used in harmful ways. This isn’t an entirely new problem. Librarians realized they had to know something about their patrons in order to be helpful. But they also knew that a deep ethical and professional obligation came with this knowledge. After some very good work by the American Library Association, librarians lobbied to have state laws passed protecting the confidentiality of their records. We don’t have anything like that for Kindle or other digital bookstores even though we should.

Selinger: So, what kind of restrictions should be placed on companies like Amazon?

Richards: Amazon is sometimes pretty good about being transparent. But we should have general transparency rules that don’t rely on the business incentives of companies, as well as rules about data use. Under current law Amazon is free to sell all of its sensitive data however it wants to, and to see why this is dangerous we only need to think about the recent Uber scandal where the company was said to be considering authorizing opposition research on the journalists who criticized it. Our intellectual privacy has real political ramifications and shouldn’t just be left to the business incentives of companies.

Selinger: Do your views on intellectual privacy shed any light on the president’s recent remarks “that police and spies should not be locked out of encrypted smartphones and messaging apps”?

Richards: The latest phase of the Snowden debate is an attack on encryption. Apple, for example, realizes it’s good business to reassure users that their sensitive data is secure, and so now it encrypts the disks on iPhones and iPads. The government responds and basically says, “Hang on, this is a problem. We need to be able to access everything. There need to be backdoors.” This is the wrong position to take because intellectual privacy requires security. We have to be able to trust people with dangerous ideas. After all, most of our cherished ideas at some point were controversial, including the idea that all people are equal before the law. Encryption provides necessary safeguards by securing what we’re thinking until we’re ready to enter public debate. I should also note that backdoors make it easier for malicious hackers to access our information. Just think about what happened to Jennifer Lawrence and Sony.

Selinger: But what the opposing view that backdoors are not synonymous with unfettered government access and their use is constrained by due process, such as warrants?

Richards: We know from Snowden and others that very often due process in national security cases is minimal to non-existent, and better checks need to be in place than the ones we currently have. Also, encryption doesn’t mean that government can’t ever get access to information, any more than putting locks on a door means that nobody can break into a house. The government’s response to this retort is that encryption makes it harder for law enforcement to do its job. But that’s exactly the point of civil liberties like intellectual privacy. They introduce inefficiencies. You know where there’s no inefficiencies? In a perfect police state! What we need is balance between freedom and security, and intellectual privacy – especially broad protections for the right to read and think freely without surveillance – must be a cherished part of that balance.

Evan Selinger is an associate professor of philosophy at Rochester Institute of Technology. Follow him on Twitter @EvanSelinger.