“1984.” “Brave New World.” “Fahrenheit 451.”

Cass Sunstein thinks the scenarios that these novels portray are going to be more of a reality if features such as the personalized shopping selections on Amazon.com, the movie suggestion feature on Netflix and personalized electronic editions of certain news sources become the way everyone buys products, chooses movies and reads news.

He is not against the Internet. That was the point launched by critics when Sunstein published the first edition of the book, “Republic.com,” which spawned hate in the blogosphere and beyond. It also garnered praise, striking a “cultural chord” with people who see politics as polarizing, most notably the red-state, blue-state divide.

In his new book, “Republic.com 2.0,” Sunstein writes, “The real goal … is to object not to any particular technology or to make a prediction about its uses, but to explore some of the preconditions of democratic self-government and to show how unrestricted free choice might undermine those preconditions.”

In other words, he wants to issue “an alert to living in an echo chamber.”

“Republic.com 2.0,” like any good second version, is “a lot better” than the first book, Sunstein said.

His new book has added section on blogs and terrorism. The latter subject is particularly gripping in its relation to Sunstein’s argument; a one-sided flow of information leads to “group polarization” and “polarization entrepreneurs,” he writes, and when terrorist leaders become such entrepreneurs, their ideology proliferates.

After criticism from his first book, Sunstein also has paid much more attention to counterarguments, which he said were very convincing. For example, Sunstein’s argument has drawn criticism from libertarians who argue that censoring the ways in which individuals can get information could possibly lead to censoring transmission of the information itself. Sunstein said he appreciates the degree to which this group dislikes regulation and acknowledges that the government shouldn’t force information distributors to circulate material they do not want to circulate.

Sunstein, the Karl N. Llewellyn distinguished service professor of jurisprudence at the University of Chicago Law School and Department of Political Science, has testified before Congress on a number of highly visible issues, including testimony against a constitutional amendment to ban same-sex marriage, against the impeachment of President Bill Clinton, and against the military’s “don’t ask, don’t tell” policy. He has worked loosely with the Bush administration on regulatory and national security issues and on the confirmation of Chief Justice John Roberts and Judge Michael McConnell.

The Harvard Law School graduate clerked for Justice Benjamin Kaplan of the Massachusetts Supreme Judicial Court and Justice Thurgood Marshall of the U.S. Supreme Court. Sunstein says Marshall was “quick — a terrific lawyer,” but not at all academic.

Sunstein later served as an attorney-adviser in the Office of the Legal Counsel of the Department of Justice during the Reagan administration, dealing with the president’s notorious court-stripping issue and firing of air traffic controllers. He was in the office when Reagan was shot, writing the memo on the post-assassination proceedings for the White House.

Reagan was “a great guy” who was, according to Sunstein, completely right on communism but superficial on domestic issues. Sunstein also had praise for his executive order regarding cost-benefit analysis and regulation.

“He stopped regulation from getting stupid,” Sunstein said of Reagan.