LEWISTON — Unseasonably cool and wet weather pushed the Bates College 147th commencement exercises indoors Sunday morning, but it couldn’t dampen the spirits of 436 graduates.

Family and friends, as well as the graduates, numbered 2,800 at Merrill Gymnasium. Overflow viewing of live video coverage was provided nearby at Olin Arts Center and Underhill Arena. The total commencement attendance on the campus amounted to more than 3,000.

Live online viewing was also possible, bringing the Bates College event to many people throughout the United States and around the world.

In his commencement address, Gary Hirshberg, co-founder and chairman of Stonyfield Farm in Vermont, told the Class of 2013 to “think differently” and always ask, “Why not?”

With tongue-in-cheek humor, Hirshberg’s commencement address related the improbable path his career took from a seven-cow organic farming school and a modest investment to an operation topping $360 million in annual sales. Since its start in 1983, Stonyfield Farm has risen to be the largest organic yogurt producer in the world.

He noted that “our most heralded financial institutions and leaders have been culpable in fueling the nation’s economic instability with short-term, greed-driven thinking.”

He told the graduates, “The bottom line is that many of the so-called experts have been wrong and now need to be second-guessed. And that is actually your job.”

Hirshberg warned that many social and ecological problems are the result of “our failure to factor long-term consequences into our thinking.” He emphasized the importance of advocating a “sustainability revolution,” adding that “your moral obligations are also your opportunity.”

He told the graduates, “You don’t have to choose between doing good and doing well. Indeed in my experience, the best ecological practices have actually turned out to be the most profitable.”

Bates College presented an honorary Doctor of Humane Letters degree to Hirshberg.

Also receiving honorary degrees from Bates were Elaine Tuttle Hansen, Doctor of Letters, who served as Bates College’s seventh president from 2002 to 2011; William Cronon, Doctor of Letters, a leading American scholar and teacher in the field of environmental history who is a powerful defender of liberal education and academic freedom; and Vivian W. Pinn, M.D., Doctor of Science, who became the first director of the National Institute of Health’s new Office of Research on Women’s Health, which was designed to advance the fair representation of women in research as both subjects and practitioners.

Pamela J. Baker, vice president for academic affairs, dean of the faculty and a member of the Bates College Class of 1969, introduced the honorands, as she has for numerous commencement ceremonies through the years. She is retiring after this academic year.

Bates Multifaith Chaplain Bill Blaine-Wallace, who delivered the Benediction, is also retiring.

In her opening remarks, Bates President A. Clayton Spencer voiced thanks to faculty, staff, and “the families and friends, by birth or choice” of the graduates.

She also paid tribute to “our friends and colleagues in Lewiston and Auburn who have enriched our days in innumerable ways.”

This year marks the first time degrees have been conferred by Spencer, who became the college’s eighth president and its second female leader last year.

In his senior address, Thomas James Holmberg III of Winnetka, Ill., told his classmates he places a high value on “the Bates mind-set” and the “beautiful cycle” of freshman to upperclassman that seems to happen in the blink of an eye. He said whenever he meets prospective Bates students, he tells them, “I can guarantee you the best years of your life here.”

The Bates College Class of 2013 includes 39 students from Maine. Among them are Yu Zhang of Auburn, who received a Bachelor of Arts in physics and mathematics; Katherine Jane DeAngelis of Lewiston, Bachelor of Science in biological chemistry; and Lundat Demissie Kassa of Lewiston, Bachelor of Arts in mathematics and economics.

There were 178 graduates from the other five New England states and 171 from 28 other states throughout the country. The class also includes 48 students from outside the U.S., representing 29 countries.

Graduates Nancy Weidner and Henry Geng, senior gift co-chairs, announced that an unprecedented 92 percent of the Class of 2013 members participated in raising nearly $18,000.

Jennifer Bouchard, Class of 1999 and president of the Alumni Council, welcomed the new graduates into the ranks of 24,000 Bates alumni.

A luncheon for graduates and their families was served at the Clifton Daggett Gray Athletic Building’s Alumni Gym following the commencement activities.