Chapman, who was a professor at the University of Texas at Austin, died Dec. 14 of a heart attack while on a kayaking trip in Guatemala, his family said.
He was "one of the early individuals writing and doing research on technology policy," specifically Internet policy, ethics and the role of the government and Internet in technology, said Sherri Greenberg, a collaborator who is the university's interim director of the Center for Politics and Governance at the LBJ School of Public Affairs.
As a high-tech philosopher, Chapman spent his professional life "looking for social justice in a community in which that phrase is distinctly remote and abstract," he wrote in 1996 in The Times.
Educated as a political scientist — he earned his bachelor's degree from Occidental College — Chapman was the first executive director of Computer Professionals for Social Responsibility, a Palo Alto-based organization concerned about the effect of computer technology on society.
As he led the group from 1984 to 1991, much of his time was spent opposing the U.S. military's reliance on inherently unreliable computers.
Eventually, the organization began addressing a broader range of issues that included automation in the workplace and how computer technology affects civil liberties and privacy.
He launched the 21st Century Project in 1991 to redirect government funding of science and technology policy from military objectives toward scientific needs, said Severo Ornstein, co-founder of Computer Professionals for Social Responsibility.
"He combined a slightly nerdy interest in computers with a broader interest in society," Ornstein said.
When Chapman joined the LBJ School of Public Affairs in 1994, the 21st Century Project came with him.
As the project's director, he helped explore ways for citizens to be engaged in policymaking that involves technology, particularly in the areas of telecommunications, the Internet and digital media, according to the university.
The first question the project confronted was how the public could become more involved in setting new goals for science and technology policy, which account for about $75 billion in federal spending each year, the project reported.
The project also addressed the digital divide — the gap between those who have access to technology and those who do not — by studying how to bring the Internet and computing to low-income neighborhoods.
With Greenberg, he recently had been researching "online transparency" and government — the idea that public information could be made more accessible on the Internet.
From 1995 to 2001, Chapman wrote a column, "Digital Nation," for The Times that was syndicated and carried by more than 200 newspapers and websites.
In the column, he foresaw a bright future as of 2000 for digital books and a year later predicted that the Internet was "headed to a very familiar technology — your television."
He also covered such topics as the "misguided" push to replace textbooks with laptops, and protecting the Internet from private and political interests.
"There aren't that many people who were as smart and analytical about the social aspects of technology as he was," said Michael Hiltzik, one of his editors at The Times. "He was important."
Chapman thought "hard about the meaning of technology, the meaning of the new world, the changes that digital technology was bringing to society," Hiltzik said. "To that extent, he was unique."
Born Aug, 8, 1952, in Los Angeles, Chapman grew up "on the flat, perfectly right-angled streets of Hawthorne in the 1950s," he wrote in The Times in 1996. His father was an aerospace engineer for Hughes.
During the Vietnam War, Chapman served as a medic for the Army Special Forces, or Green Berets, and later expressed amusement that this fact invariably fascinated people.
In 1979, he graduated from Occidental, which will fly its college flag at half-staff in his honor for a day in early January.
He also did postgraduate work in political science at Stanford University in 1984.
At the University of Texas, he was one of the most popular professors, said Robert Hutchings, dean of the LBJ School of Public Affairs.
"He was unusual. He could go long periods without speaking and was not troubled by unpleasant silences," Hutchings said. "When Gary Chapman spoke, everyone listened. He was always reasoned, always thoughtful and always advanced the conversation to a place it hadn't been before."
Chapman is survived by his wife, Carole Flake Chapman, a journalist; his father, Arthur S. Chapman, and stepmother, Pierrette Chapman, of Solvang; and a half-brother, Duane Chapman, of Bakersfield.