This year, we lost three giants in the psychological science community, all relevant to our work here at Greater Good. Frans de Waal, Daniel Kahneman, and Philip Zimbardo each passed away in 2024, leaving behind important contributions to understanding human nature and how to live our lives with more Self-awareness, empathy, and altruism.

Frans de Waal: Caring primatologist

De Waal, who passed away on March 14, 2024, at 75 years old, started his career as a primatologist, studying apes in captivity to learn about their social relationships and habits. In 1981, he moved from the Netherlands (his original home) to the University of Wisconsin, Madison, to join their National Primate Research Center. Later, he moved to Emory University, where he finished his academic career directing the Living Links Center for the Advanced Study of Ape and Human Evolution and acting as a professor of psychology. He left behind a treasure trove of research shedding light on the evolutionary basis for empathy and compassion.

De Waal was a special friend to the Greater Good Science Center, serving on our editorial board. I first heard of him when I began working for Greater Good magazine in 2005. He’d written a book called Our Inner Ape, which I read and reviewed for our (then print) publication. De Waal had carefully studied the behavior of chimpanzees and bonobos, our closest primate relatives, and written about how they navigated their conflicts and made peace with one another.

In the course of his work, he’d discovered that while some apes were more aggressive and unfriendly to strangers, others displayed great empathy and seemed to value fairness and kindness. His observations, as outlined in his book, supported a more nuanced view of our evolutionary heritage and a sense that we humans had two paths to choose from going forward—a more aggressive, competitive path or a kinder, more compassionate path.

De Waal went on to write several other highly influential books, including some we reviewed in Greater Good: The Age of Empathy and Mama’s Last Hug. These books made the case that humans may be less special or supremely evolved than we think we are and that animals are also capable of Self-awareness, love, and altruism.

His books have been influential in fostering interest not only in animal emotions and behaviors for their own sake, but also in bettering our relationship to the natural world we inhabit, including its animal residents. His legacy lives on in countless other scientists taking up the same cause for treating our animal brethren with care and respect.

Daniel Kahneman: Pioneering behavioral economist

Kahneman was the emeritus professor of psychology and public affairs at Princeton University when he passed away at 90 years old on March 27, 2024. He made many important contributions to the field, helping us better understand our decision making, especially under circumstances involving uncertain outcomes.

Though Kahneman was not directly affiliated with Greater Good, his research on the relevance of wealth to happiness, as well as how people make economic judgments and decisions, has been relevant to our work and influenced countless other researchers throughout his career. By integrating psychology research findings with economic science, he launched a new field of inquiry, behavioral economics—a feat that won him the Nobel Prize for Economics in 2002, despite never having formally studied economics in school.

I first learned of Kahneman’s work by reading his book Thinking Fast and Slow and reviewing it for our magazine. This groundbreaking, bestselling book helped explain why economists’ view of people as rational, self-interested actors making calculated economic decisions was dead wrong. Instead, as Kahneman and his colleague Amos Tversky found through their research, human motivations are much more complex than that, involving other modes of thinking and less-than-perfect forecasting of outcomes.

As Kahneman wrote in his book, people often resort to cognitive shortcuts when evaluating choices and making decisions, relying on their biases and intuitions (or what he called “fast thinking”) rather than slower, deliberate thinking. This sometimes results in good outcomes and sometimes doesn’t. By shedding light on these processes, he helped us understand better how cognitive bias works, how our emotional states affect our behaviors, and how to nudge ourselves (and others) toward wiser choices.

Kahneman also contributed to the study of “happiness forecasting,” or how we make predictions about what will make us happier—which, as it turns out, is not our strong suit. He helped encourage well-being researchers to rely less on people’s memory of their happiness looking back and, instead, consider in-the-moment measures to provide a more accurate sense of what makes people happy. By better understanding how our emotions and cognitions are intertwined, Kahenman has helped us make huge strides in self-understanding, as well as laying the groundwork for creating better economic policy for all.

Philip Zimbardo: Scientist of human nature

Psychologist Zimbardo, a friend to Greater Good, passed away on October 14, 2024, at the age of 91. Though he had teaching stints at several top universities, his career at Stanford University, beginning in 1971, cemented his fame around the world.

Like many other psychology students, I’d originally heard his name in association with the Stanford Prison Experiment—a study often recounted in psychology textbooks. In the study, students role-played being “guards” or “prisoners” in a fake prison setting to see how social roles affected behavior. Over the course of the experiment, without much prompting, “guards” began bullying and mistreating their “prisoners,” causing Zimbardo to halt the experiment early.

The conclusion he drew from his study was that ordinary people could be driven to act with cruelty when given power over others by authoritarian figures. This finding was widely publicized and used to support the “banality of evil” hypothesis, which helped explain how ordinary citizens in Germany could be persuaded to turn away from their moral instincts and support a hateful regime like the Nazis.

Later, other researchers questioned the validity of Zimbardo’s conclusions, saying that some students left the study early and those who didn’t were often play-acting to help the researchers—in other words, not actually becoming cruel monsters.

While Zimbardo himself never refuted his famous findings, believing they helped us understand bystanders to evil, he did change tack somewhat in his later years. Instead of looking at the banality of evil, he began focusing more on the flip side of that research—understanding the banality of heroism, or how ordinary people could act heroically in the face of injustice and cruelty. Eventually, he founded the Heroic Imagination Project in San Francisco, which has helped train tens of thousands of people on how to act courageously and heroically when faced with challenges in their communities.

I was lucky enough to hear Zimbardo speak at a GGSC event and was inspired by his passion for promoting everyday heroism—something very akin to our goals at Greater Good. I feel grateful to him—and to Kahneman and de Waal—for what they did to shape the field of positive psychology. In their own ways, they helped encourage a more humane future, one in which we value all life, make better choices, and stand up for those who are helpless. May their work continue to resonate in the years ahead as we navigate future challenges and are called upon to be wise, courageous, empathic citizens of the world.