Harvard Law School Professor Cass R. Sunstein ’75 talks about his new best-selling book at the First Parish Church in Cambrigdge, yesterday.

Harvard Law School professor Cass R. Sunstein ’75 entertained a large crowd of listeners at the First Parish Church last night, who came to hear the legal superstar discuss his best-selling book “Nudge: Improving Decisions About Health, Wealth, and Happiness.”

The event was hosted by Cambridge Forum, a local public affairs radio program, and was recorded for later broadcast on National Public Radio.

Cambridge Forum Director Patricia Suhrcke introduced Sunstein and Harvard Business School professor Alvin E. Roth served as moderator for the event.

“When I found out that Professor Sunstein was coming to Harvard last spring, I wrote and invited him to talk. I had read about ‘Nudge’ and I had known his legal writings for years,” Suhrcke said.

Sunstein began his talk by honoring Roth, calling him “one of my heroes.” He later joked, “To see so many people come out to talk about these issues—we must be in the midst of a financial crisis.”

Sunstein explained the central concept of his philosophy of “libertarian paternalism,” which he developed with University of Chicago economics professor Richard H. Thaler.

The philosophy involves altering the social context in which people make decisions in order to guide them to choose more beneficial outcomes subconsciously.

As an example, he referenced the Dutch practice of painting a house fly on the inside of airport urinals. This resulted in an 80 percent reduction in overall “spillage,” because men subconsciously aimed for the etching.

In other cases, the rearrangement of food options in cafeterias and the practice of opting out of 401(k) plans have had “subtle, sometimes damaging, sometimes wonderfully beneficial effects on our behavior.”

The audience posed a number of questions to Sunstein. They asked him about his views on president-elect Obama, whom Sunstein has advised, and questioned him on the value of the “nudge” method in affecting smoking and environmental change.

Attendees seemed quite pleased with the talk.

“I thought it was a very good introduction,” Harvard Law student Samantha A. Crane said of Sunstein, adding, “I really like his idea.”

Cambridge resident Kathy Reine agreed, saying, “I thought it was a terrific talk. Decisions are painful. People like all the help they can get.”

“I felt the audience was fantastic, both in size and in quality,” Sunstein said. “The people asked great questions, and to see people engaged on issues of law and human behavior and social science was great.”