Aryeh Kosman, 85, a retired Haverford College philosophy professor renowned for deep engagement with students and insightful writings on Plato and Aristotle, died Thursday, June 17, at Bryn Mawr Hospital from complications after a fall.

“He was the most remarkable teacher,” said Jim Friedman, a 1967 Haverford graduate who spent the last 15 years regularly reading and discussing philosophy with Dr. Kosman. “Haverford’s a place — was and still is — with a lot of remarkable teachers. He stood out. He was just the most wonderful human being. It’s a huge loss.” They had planned to discuss Wittgenstein over Zoom on the day Dr. Kosman died.

As a scholar, Dr. Kosman made lasting contributions to the study of Aristotle’s ethics and metaphysics, colleagues said.

“His work, a brilliant combination of careful analysis and imaginative overview, captures in clear and elegant terms some of the most difficult and elusive aspects of Plato’s and Aristotle’s thought in a way which makes them accessible to a wider philosophical audience,” said David Charles, a philosophy professor at Yale University.

Dr. Kosman, who was born in Oakland, Calif., as Louis Bernard Kosman, changed his middle name to Aryeh as a young adult after becoming interested in Jewish observance, eventually publishing under that name, his son Joshua said.

After joining Haverford’s faculty in 1962, with a Ph.D. in philosophy from Harvard University, Dr. Kosman stood out with what the young professor described as a “beatnik beard.” He was included in a 1966 Esquire magazine article about “Super-Profs” who were infusing America’s colleges with new vitality, and participated in campus protests against the Vietnam War, according to his son.

For many years, Dr. Kosman, a Haverford resident, was faculty marshal at Haverford graduations. That required him to announce the name of each graduate. It was a task he took seriously: Weeks before the ceremony, he set up an answering machine in his office and asked prospective graduates to leave a message with the correct pronunciation of their names, his son said. Then he practiced.

Dr. Kosman, who retired in 2010 but continued writing and lecturing, made deep impressions on students and younger scholars, who recalled on Twitter and philosophical forums how much they learned from him and appreciated his guidance.

John Parachini, who graduated from Haverford in 1982 as a philosophy major and is now a researcher at Rand Corp., recalled how in Dr. Kosman’s course on Aristotle’s Metaphysics they would read a paragraph per class. “He had a way of teasing out the richness of it and the complexity of it,” Parachini said.

James Lennox, a retired philosophy professor at the University of Pittsburgh and a friend of Dr. Kosman’s since the 1980s, recalled sharing with Dr. Kosman “a love of movies, a love of poetry, a love of good food, good wine, a love of just sitting around having conversations that would wander all over the map.”

In addition to his son, Dr. Kosman is survived by his wife, Deborah Roberts, who retired last month as a professor of classics at Haverford; sons Isaac and Jacob; a daughter, Hannah; his first wife, Tracy Kosman; four grandchildren; and two brothers.

A funeral was held on Friday, June 18, at Temple Beth Hillel-Beth El, in Wynnewood. The family plans a memorial service at a later date.

Contributions in his honor may be made to Bryn Mawr Hospital, the New Israel Fund, or the American Civil Liberties Union.