Jens Ludwig has an idea for how to fix America’s gun violence problem — and it starts by rejecting conventional wisdom from both sides of the political aisle. 

• SOURCES:
  • Jens Ludwig, professor of economics at the University of Chicago and director of the University of Chicago Crime Lab.

• RESOURCES:
  • Unforgiving Places: The Unexpected Origins of American Gun Violence, by Jens Ludwig (2025).
  • "Scope Challenges to Social Impact," by Monica Bhatt, Jonathan Guryan, Jens Ludwig, and Anuj Shah (National Bureau of Economic Research, 2021).
  • "Citywide cluster randomized trial to restore blighted vacant land and its effects on violence, crime, and fear," by Charles Branas, Eugenia South, Michelle Kondo, Bernadette Hohl, Philippe Bourgois, Douglas Wiebe, and John MacDonald (Proceedings of the National Academy of Sciences, 2018).
  • "Thinking, Fast and Slow? Some Field Experiments to Reduce Crime and Dropout in Chicago," by Sara Heller, Anuj Shah, Jonathan Guryan, Jens Ludwig, Sendhil Mullainathan, and Harold Pollack (Quarterly Journal of Economics, 2016).
  • Thinking, Fast and Slow, by Daniel Kahneman (2013).
  • "Homicide and Suicide Rates Associated With Implementation of the Brady Handgun Violence Prevention Act," by Jens Ludwig and Philip Cook (Journal of the American Medical Association, 2000).
  • The Death and Life of Great American Cities, by Jane Jacobs (1992).
  • The University of Chicago Crime Lab.
  • "Becoming a Man" (University of Chicago Crime Lab).

• EXTRAS:
  • "Do the Police Have a Management Problem?" by Freakonomics Radio (2023).
  • "From prison to Ph.D, this activist fights for peace in Chicago," by Kenya Downs (PBS News, 2016).

Ellen Wiebe is a physician who helps seriously ill patients end their lives in Canada, where assisted suicide is legal. Is death a human right?

• SOURCES: 
  • Ellen Wiebe, clinical professor of medicine at the University of British Columbia.

• RESOURCES: 
  • "The Last Decision by the World’s Leading Thinker on Decisions," by Jason Zweig (The Wall Street Journal, 2025).
  • "Most Americans Favor Legal Euthanasia," by Rachael Yi (Gallup, 2024).
  • Canadian Association of MAID Assessors and Providers.
  • "Medical Assistance in Dying: Overview," (Government of Canada).

• EXTRAS: 
  • "Can Robots Get a Grip?" by People I (Mostly) Admire (2025).
  • "Remembering Daniel Kahneman," by People I (Mostly) Admire (2024).
  • "Does Death Have to Be a Death Sentence?" by People I (Mostly) Admire (2021).
  • Thinking, Fast and Slow, by Daniel Kahneman (2011).

He has been a lawyer, an instructor at the F.B.I. Academy, the owner of a frozen-yogurt chain, and a winner of the TV show Survivor. Today, Kwon works at Google, but things haven’t always come easily for him. Steve Levitt talks to Kwon about his debilitating childhood anxieties, his compulsion to choose the hardest path in life, and how Kwon used game theory to stage a victory on Survivor.

• SOURCES:
  • Yul Kwon, vice president of product management at Google.

• RESOURCES:
  • Teacher Application for ASU Prep Tempe.

• EXTRAS:
  • "Are Our Tools Becoming Part of Us?" by People I (Mostly) Admire (2024).
  • "Yul Kwon: 'Hey, Do You Have Any Bright Ideas?' (Part 2)," by People I (Mostly) Admire (2021).
  • "Robert Axelrod on Why Being Nice, Forgiving, and Provokable are the Best Strategies for Life," by People I (Mostly) Admire (2021).

Ken Goldberg is at the forefront of robotics — which means he tries to teach machines to do things humans find trivial.

• SOURCES:
  • Ken Goldberg, professor of industrial engineering and operations research at U.C. Berkeley.

• RESOURCES:
  • "The Bitter Lesson," by Rich Sutton (UT Austin, 2019).
  • R.U.R. (Rossum's Universal Robots): A Fantastic Melodrama in Three Acts and an Epilogue, by Karel Capek (2019).
  • "The Robot in the Cloud: A Conversation With Ken Goldberg," by Quentin Hardy (New York Times, 2014).
  • Mind Children: The Future of Robot and Human Intelligence, by Hans Moravec (1990).
  • "Stochastic Plans for Robotic Manipulation," by Ken Goldberg (Carnegie Mellon University, 1990).
  • "The Two Cultures And The Scientific Revolution," by C. P. Snow (Cambridge University Press, 1959).
  • Dex-Net
  • Ancient Wisdom for a Future Ecology: Trees, Time, and Technology.
  • Ambi Robotics.
  • "The Telegarden."

• EXTRAS:
  • "Feeling Sound and Hearing Color," by People I (Mostly) Admire (2024).
  • "Are Our Tools Becoming Part of Us?" by People I (Mostly) Admire (2024).
  • “My God, This Is a Transformative Power,” by People I (Mostly) Admire (2023).
  • "Drawing from Life (and Death)" by People I (Mostly) Admire (2023).
  • "Aicha Evans Wants You to Take Your Eyes Off the Road," by People I (Mostly) Admire (2021).

Suzanne O'Sullivan is a neurologist who sees many patients with psychosomatic disorders. Their symptoms may be psychological in origin, but their pain is real and physical — and the way we practice medicine, she argues, is making those and other health problems worse.

• SOURCES:
  • Suzanne O'Sullivan, neurologist and author of The Age of Diagnosis How Our Obsession with Medical Labels Is Making Us Sicker.

• RESOURCES:
  • The Age of Diagnosis: How Our Obsession with Medical Labels Is Making Us Sicker, by Suzanne O'Sullivan (2025).
  • "Associations of Depression, Anxiety, Worry, Perceived Stress, and Loneliness Prior to Infection With Risk of Post-COVID-19 Conditions," by Siwen Wang, Luwei Quan, Jorge Chavarro, Natalie Slopen, Laura Kubzansky, Karestan Koenen, Jae Hee Kang, Marc G. Weisskopf, Westyn Branch-Elliman, and Andrea Roberts (JAMA Psychiatry, 2022).
  • "How beliefs about coronavirus disease (COVID) influence COVID-like symptoms? – A longitudinal study." by Liron Rozenkrantz, Tobias Kube, Michael H Bernstein, and John D.E. Gabrieli (Health Psychology, 2022).
  • "Risk factors for worsening of somatic symptom burden in a prospective cohort during the COVID-19 pandemic," by Petra Engelmann, Bernd Löwe, Thomas Theo Brehm, Angelika Weigel, Felix Ullrich, Marylyn Addo, Julian Schulze Zur Wiesch, Ansgar Lohse, and Anne Toussaint (Frontier Psychology, 2022).
  • The Sleeping Beauties: And Other Stories of Mystery Illness, by Suzanne O'Sullivan (2021).
  • Brainstorm: Detective Stories from the World of Neurology, by Suzanne O'Sullivan (2018).
  • "The Trauma of Facing Deportation," by Rachel Aviv (The New Yorker, 2017).
  • It's All in Your Head: True Stories of Imaginary Illness, by Suzanne O'Sullivan (2015).
  • The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma, by Bessel van der Kolk (2014).
  • "Explaining the Rise in Youth Suicide," by David Cutler, Edward Glaeser,
    and Karen Norberg (National Bureau of Economic Research, 2001).

• EXTRAS:
  • Counted Out, documentary (2024).
  • "Bringing Data to Life," by People I (Mostly) Admire (2023).
  • "Adding Ten Healthy Years to Your Life," by People I (Mostly) Admire (2023).
  • "America’s Math Curriculum Doesn’t Add Up," by Freakonomics Radio (2019).
  • Race to Nowhere, documentary (2010).
  • Data Science for Everyone.

Reginald Dwayne Betts spent more than eight years in prison. Today he's a Yale Law graduate, a MacArthur Fellow, and a poet. His nonprofit works to build libraries in prisons so that more incarcerated people can find hope.

• SOURCES:
  • Reginald Dwayne Betts, founder and director of Freedom Reads, award-winning poet, and lawyer.

• RESOURCES:
  • Doggerel: Poems, by Reginald Dwayne Betts (2025).
  • “The Poet Writing on Prison Underwear,” by Adam Iscoe (The New Yorker, 2023).
  • The Voltage Effect, by John List (2022).
  • “If We Truly Believe in Redemption and Second Chances, Parole Should Be Celebrated,” by Reginald Dwayne Betts (The Washington Post, 2021).
  • Insurrections, by Rion Scott (2016).
  • The Secret History of Wonder Woman, by Jill Lepore (2014).
  • Zen and the Art of Motorcycle Maintenance: An Inquiry into Values, by Robert M. Pirsig (1974).
  • The Black Poets, by Dudley Randall (1971).
  • “For Freckle-Faced Gerald,” by Etheridge Knight (Poems from Prison, 1968).
  • Felon: An America Washi Tale, by Reginald Dwayne Betts.
  • Freedom Reads.

• EXTRAS:
  • “Can a Moonshot Approach to Mental Health Work?” by People I (Mostly) Admire (2023).
  • “Can Data Keep People Out of Prison?” by People I (Mostly) Admire (2023).
  • “The Price of Doing Business with John List,” by People I (Mostly) Admire (2022).
  • “Why Do Most Ideas Fail to Scale?” by Freakonomics Radio (2022).

Chemist Jack Szostak wants to understand how the first life forms came into being on Earth. He and Steve discuss the danger of "mirror bacteria," the origin of biology in poisonous chemicals, and the possibility that life might exist on other planets too. 

• SOURCES:
  • Jack Szostak, Nobel laureate and professor of chemistry at The University of Chicago.

• RESOURCES:
  • Is Earth Exceptional?: The Quest for Cosmic Life, by Mario Livio and Jack Szostak (2024)
  • "Q&A: How ‘Mirror Bacteria’ Could Take a Devastating Toll on Humanity," by Isabella Backman (Yale School of Medicine, 2024).
  • "The virtual circular genome model for primordial RNA replication," by Jack Szostak, Lijun Zhou, and Dian Ding (RNA, 2021).
  • "Protocells and RNA Self-Replication," by Gerald Joyce and Jack Szostak (Cold Spring Harbor Perspectives in Biology, 2018).
  • "The Narrow Road to the Deep Past: In Search of the Chemistry of the Origin of Life," by Jack Szostak (Angewandte Chemie International Edition, 2017).
  • "Jack Szostak on 'Life in the Lab' (And Autocatalytic Sets)" by Suzan Mazur (Huffington Post, 2014).
  • "Jack W. Szostak Interview" (The Nobel Prize, 2009).
  • "The Miller-Urey Experiment" (National Center for Science Education).
  • "From Old Vials, New Hints on Origin of Life," by Kenny Chang (New York Times, 2008).

• EXTRAS:
  • What Is It Like to Be an Addict?: Understanding Substance Abuse, by Owen Flanagan (2025)
  • "UPDATE: What It’s Like to Be Steve Levitt’s Daughters," by People I (Mostly) Admire (2024).
  • "We Can Play God Now," by Freakonomics Radio (2022).

Owen Flanagan's newest book details his 20-year dependence on alcohol and pills — and outlines his research on what addiction can tell us about the nature of consciousness.

• SOURCES:
  • Owen Flanagan, philosopher, neurobiologist, and professor emeritus at Duke University.

• RESOURCES:
  • What Is It Like to Be an Addict?: Understanding Substance Abuse, by Owen Flanagan (2025).
  • Consciousness Reconsidered, by Owen Flanagan (1993).
  • Against Happiness, by Owen Flanagan, Joseph E. LeDoux, Bobby Bingle, Daniel M. Haybron, Batja Mesquita, Michele Moody-Adams, Songyao Ren, Anna Sun, and Yolonda Y. Wilson. (2023).
  • The Bodhisattva's Brain: Buddhism Naturalized, by Owen Flanagan (2013).
  • The Really Hard Problem: Meaning in a Material World, by Owen Flanagan (2009).
  • Big Book, by Alcoholics Anonymous.
  • "Impact of the DSM-IV to DSM-5 Changes on the National Survey on Drug Use and Health," by Cristie Glasheen, Kathryn Batts, Rhonda Karg, Jonaki Bose, Sarra Hedden, and Kathryn Piscopo (Substance Abuse and Mental Health Services Administration, 2016).

• EXTRAS:
  • "Professor Carl Hart Argues All Drugs Should Be Legal — Can He Convince Steve?" by People I (Mostly) Admire (2021).
  • Drug Use for Grown-Ups: Chasing Liberty in the Land of Fear, by Carl Hart (2021).

The primatologist discusses the thrill of observing chimpanzees in the wild, the value of challenging orthodoxy, and why dying is her next great adventure.

• SOURCES:
  • Dr. Jane Goodall, GBE, founder of the Jane Goodall Institute and U.N. Messenger of Peace.

• RESOURCES:
  • The Book of Hope: A Survival Guide for Trying Times, by Jane Goodall, Douglas Abrams, and Gail Hudson (2021).
  • Jane, by Brett Morgen (2017).
  • “Remembering My Mentor: Robert Hinde,” by Jane Goodall (2017).
  • The Soul of an Octopus: A Surprising Exploration into the Wonder of Consciousness, by Sy Montgomery (2015).
  • Dr. Spock On Parenting: Sensible, Reassuring Advice for Today’s Parent, by by Benjamin Spock, M.D. (2001).
  • The Mentality of Apes, by Wolfgang Kohler (1976).
  • “Miss Goodall and the Wild Chimpanzees,” (1965).

• EXTRAS:
  • Roots and Shoots.
  • Jane Goodall Hopecast.
  • The Jane Goodall Institute.
  • Grameen Foundation.
  • “A Cross Between Sherlock Holmes and Indiana Jones,” by People I (Mostly) Admire (2022).
  • “‘No One Can Resist a Jolly, Happy Pig,'” by People I (Mostly) Admire (2022).

Hank Green is an internet phenomenon and a master communicator, with a plan to reform higher education. He and Steve talk about the video blog that launched Hank’s career, the economics of the internet, and how a cancer diagnosis prompted him to become a stand-up comedian.

• SOURCES:
  • Hank Green, founder of Complexly and science communicator

• RESOURCES:
  • Complexly
  • CrashCourse YouTube Channel
  • SciShow YouTube Channel
  • Vlogbrothers YouTube Channel
  • The Show with Ze Frank
  • Study Hall
  • "An Absolutely Remarkable Thing," by Hank Green (2018)
  • "A Beautifully Foolish Endeavor," by Hank Green (2020)
  • "So, I've got cancer," by Vlogbrothers (2023)
  • "My Cancer Press Tier List," by Vlogbrothers (2023)
  • "Between Two Kingdoms: A Memoir of a Life Interrupted" by Suleika Jaouad (2021)
  • "The Impact of Legalized Abortion on Crime," by John Donohue III and Steve Levitt (The Quarterly Journal of Economics, 2001)
  • "Hoodwinked?" by Stephen Dubner and Steve Levitt (New York Times, 2006)
  • "An Ancient Roman Shipwreck May Explain the Universe," by SciShow (2024)

• EXTRAS:
  • "John Green’s Reluctant Rocket Ship Ride," by People I (Mostly) Admire (2022)
  • "Suleika Jaouad’s Survival Mechanisms," by People I (Mostly) Admire (2024)