Shelly Kagan sits cross-legged on a table at the front of the room, introducing the trolley problem for the thousandth time. He wears blue jeans and black converse sneakers. He asks that his students call him by his first name. All is at peace. Suddenly, a hand goes up. He bounces off the table, responding with a joy and earnestness befitting the expectation of discovery.

This exuberant style captures what makes Kagan charming to audiences around the world. He treats philosophy not as an ivory tower indulgence, but as a lively activity for everyone.

Every year Kagan’s “Introduction to Ethics” course draws over a hundred undergraduates; his Bulldog Days lecture causes Battell Chapel to overflow with prospective students. His recorded lectures on the philosophy of death have been viewed more than thirty million times in China, and his book based on that lecture series, Death (2012), was a national bestseller in South Korea. In a word, Shelly Kagan is the closest figure Yale has to a public philosopher.

Kagan did not carefully sculpt his persona or make detailed career plans. In fact, sitting down with Kagan reveals one striking quality: spontaneity. His speech is off-the-cuff, with an intonation that makes each string of sentences feel like a journey of grasping a kernel of the truth, losing it, and starting over again. Kagan is like this at all times, from a casual conversation in office hours to the seminar room. The free-wheeling approach is completely natural to him.

At the root of Kagan’s energetic demeanor is a deep love for his craft. Philosophy for him has never been a mere occupation defined by his contribution to academic literature. Instead, Kagan’s motive has always been to seek the answers to big, enduring questions. It is from this original curiosity that everything—his style, his analytic rigor, his love of intellectual community—follows.

FROM RELIGIOUS STUDIES TO PHILOSOPHY

Kagan was interested in Jewish religious thought from an early age. Philosophy first drew his interest in high school after struggling to understand Martin Buber and Søren Kierkegaard’s commentaries on Genesis. “There was a considerable discussion of philosophical ideas that I was unfamiliar with,” Kagan said, “so I started reading philosophy.”

Kagan entered Wesleyan College in 1972 as a religion major and had plans to become a rabbi. Yet, a strong sense of community brought philosophy from the periphery to the center of his thinking. Kagan explains that at Wesleyan, philosophy majors often hung out in their department’s lounge talking to one another. In contrast, the religious studies building did not have a common area. As a result, he spent most of his intellectual life with fellow philosophy majors.

Kagan’s love of philosophy is inextricably linked to community. During his childhood, Kagan had a propensity to ask questions which sometimes left him on the social margins. “Finding philosophy was discovering there are other people who think the way I do and share my interest in thinking about ethics and the meaning of life,” Kagan said. After completing his studies at Wesleyan, Kagan pursued a PhD at Princeton, where his community grew. “We’d hang out and argue philosophy together constantly,” Kagan said of his doctoral cohort.

At Princeton, Kagan studied under two prominent philosophers: Thomas Nagel and Derek Parfit. “Tom really worked hard to teach me about philosophical depth, to not be satisfied with scoring quick superficial points,” Kagan recalled. This included cultivating Kagan’s ability to work through and understand the heart of a philosophical problem. During this time, Kagan practiced seeing issues from different perspectives, including ones he didn’t necessarily endorse. He frequently asked himself, “What kind of assumptions would make that an attractive position? What would it look like to view the world that way?”

After graduating from Princeton, Kagan taught at the University of Pittsburgh and the University of Illinois Chicago (UIC), before eventually making his way to Yale.

RISING TO FAME

Kagan began his career focusing on debates in moral philosophy such as the nature of well-being, the limits of morality, and the role of desert in our ideas of justice. He first developed an interest in death during his time at UIC, when the department asked if he wanted to revive a past class on the subject. Death affects everyone and connects to numerous other topics in philosophy such as personal identity, value theory, and the nature of emotions. Kagan believed it would make a wonderful introduction to philosophy. After devising a new syllabus, he began teaching the class at UIC and continued teaching it at Yale.

When Open Yale Courses approached him about recording his lecture course on death, Kagan did not expect much. Launched in 2007, Open Yale Courses was a project of Yale University to provide free and open access to video and course material from undergraduate courses. At the time, few universities were publishing class lectures on the internet for free. “Nobody had a real idea for the audience for them. I thought maybe about a half dozen kids in some dorm may look at the videos,” Kagan said.

Just a few years after Open Yale Courses published them, Kagan’s lectures had millions of views. His 2012 publication of Death, the book written after the course, sold over 230,000 copies in foreign editions and became a national bestseller in South Korea. The response was stunning. Kagan received emails from people around the world, from all walks of life. These messages ranged from brief thank-you notes to detailed refutations of arguments he referenced in his lectures. “I was completely blown away by how popular my death lectures had become,” Kagan said.

The interest around Kagan’s work snowballed far beyond the classroom. In 2010, China National Radio reported, “[Kagan’s] image, resembling that of an ‘immortal’ in Chinese mythology, has made him a ‘star’ closely followed by the youth in China.” His weekend workshop at the Yale Center Beijing was streamed live by 25,000 people, and during his visits, people lined up around blocks to get their books autographed. Kagan also appeared on South Korean radio and television, including a game show with a sold-out crowd of 3,000 people. To mimic the style of his lectures, the hosts even laid out a box on which Kagan could sit cross-legged.

Kagan’s likeness also began to be used in the arts—in rather unexpected ways. In New York, there was an experimental 2014 play about him called PHIL 176 / OBIT. “The play basically consisted of somebody being me,” Kagan explained. Each day in the play, the actor gave one of my lectures. So for two weeks he gave half of the lectures from my death class.”

Japanese manga writers have planned to make a manga inspired by his course. Yale University Press and then Dean of Yale College Marvin Chun contacted Kagan to see if he approved of the usage. While Kagan anticipates the writers will only capture a fraction of his course’s content, his response was emphatic. “Are you crazy? Of course, I’m going to let them do this. Who’s ever wanted to make a graphic novel about me before?”

Kagan remains grounded amid the uptick in profile. Even now, the interest in his work surprises him. Most of all, though, he feels appreciative: “The thought that the things that I published could have made a difference to people—it has just been an amazing, gratifying experience.”

A LOVE FOR BIG QUESTIONS

Fame has not changed Kagan’s scholarly agenda. He still concentrates on moral philosophy, though he has explored new subjects like the ethical status of animals and moral skepticism.

His attitude towards academic work is distinctive. “There’s a spectrum in terms of how much one’s philosophizing is a reaction to the literature, and how much it’s just being spun out of their own mind,” Kagan explained. “I’m much more of the latter. And that means I don’t spend a lot of time reading literature, which includes people that are responding to me.”

This attitude is a departure from a tendency in academia to emphasize contributions to existing literature and journal citations. Yet, it attests to the way Kagan has maintained his curiosity throughout his work. Even as he maneuvers the minute details and arguments of a topic, he never loses sight of the purpose of the endeavor—to ultimately answer an important question. This approach has helped Kagan drive meaningful conversations with different audiences.

“Almost every philosophical problem grows out of a certain kind of puzzle that any ordinary person will, at one time or another, ask themselves,” Kagan said. “How do we know anything? What’s the world really like? There’s a part of you that is still pulled by these questions. If you want answers to them, you’ll do better to try to explore them.”

This reasoning forms the basis for Kagan’s belief that philosophy is important for Yale students. The discipline offers a systematic way of studying and thinking about human nature and obligation.

“In college, you’re trying to decide who you are going to be,” Kagan explained. “You try on different worldviews for size. You check out different ideas and build up a set of values. Philosophy gives you alternative pictures that some of the greatest minds in history have come up with about what is a person? How should we live? What do we owe one another?”

Philosophy demands that we bring our actions in line with our beliefs. Kagan has taken this to heart. He became a vegetarian, for example, after “reading certain philosophical essays talking about the moral standing of animals.”

“It turns out fish are far more intelligent than I’ve ever given them credit for. So when I combined that with my moral views on why you should not eat beef, pork, chicken—suddenly, I had to give a face. So I gave up fish,” Kagan said of his dietary switch. The spirit of moral philosophy is not abstract argumentation but searching for truths. They create our obligations.

TEACHING AT YALE

While Kagan runs classes with his own flair, it took a few years at Yale before he found his rhythm. Kagan admits that in seminars he had to learn to give students space for discussion. “I love to talk. When students say something interesting in class, my knee-jerk reaction is to jump in and start talking with them. But since my goal in class is to get the students talking to each other, I need to constantly remind myself to keep more of my thoughts to myself.”

Lecturing has always come more easily to him than facilitating discussion. He does not read from a paper. Instead, he has a set of notes that he reviews before class. Otherwise, he’s just “thinking out loud in front of students.” As a result, his lectures change from year to year.

“I think of it a little bit like being a jazz performer. There’s a basic score that you’re riffing on, so any given performance will recognizably have the same melody as the last one, but on different occasions you expand on a part or cut an element out.”

Kagan has taught introductory ethics for over three decades. When asked if he ever gets tired of it, he smiled. “I only get to give a specific lecture once a year,” he reminded me. “A single lecture is like a piece of music I’m fond of and which I only get to play once a year. Far from being boring, it’s something I look forward to.”

While Kagan is a beloved educator, many students hesitate to register for his courses, especially the seminars. In the past, almost half of students have chosen to Credit/D/Fail his classes. Kagan is aware of his reputation as a difficult grader. He recognizes that his grading methodology demands certain responsibilities from him, including clear and detailed feedback.

Kagan’s support on papers carries the same spirit as when he stays up to an hour after class to answer every person’s last question. He has often “written more comments in terms of sheer number of words than the paper itself.” Kagan offers directions a paper could have taken, objections it might have considered, and comments on the specific aspects of the argument that succeeded and failed. “If I’m going to hold people to serious standards, I need to give them sufficiently detailed feedback so that they can meet those standards,” Kagan said.

LOOKING INTO THE FUTURE

It may seem an odd fact that some of the greatest philosophers, from Aristotle to Epicurus, have spilled ink on the subject of friendship. Yet, it is an important reminder that some of the ideas we take for granted can be the sustaining force behind our passion. Not only does friendship fulfill our basic desire to be accepted, but it clarifies our beliefs and how we understand ourselves.

Looking beyond his reputation and his storied quirks, what defines Kagan as an academic is a sincere love of discussing ideas with others.

This fact shows when he talks about his former students. His voice softens. Teaching philosophy has a meaning that transcends the halls of winning or losing a debate. Kagan says that his most rewarding moments come when alumni—ranging from one year to twenty years after graduation—write to tell him that his class impacted their lives. “When students tell me, ‘your class taught me how to think’ or ‘you changed my views in ways I didn’t appreciate at the time,’ I am moved beyond words. I am touched,” he said.

When asked if he had any plans to retire, Kagan smiled. Grateful to read books and discuss philosophy with curious and eager students, Kagan said he would like to teach for as long as possible. After all these years, the flame of his curiosity burns strong, with the same vigor of his own college years. “Philosophy is a never-ending feast of things to think about—an endless source of amazement, challenge, and bafflement.”