Radiolab: "Killing Babies, Saving the World"

Release Date: November 17, 2009
Hosts: Jad Abumrad, Robert Krulwich
Guest: Joshua Greene (Assistant Professor of Psychology at Harvard University)

Episode Overview

This episode of Radiolab dives into the complexities of moral reasoning, specifically how we make gut-wrenching decisions that pit personal love against the greater good. Revisiting an infamous ethical dilemma—would you smother your own baby to save a group of people?—the hosts, joined by psychologist Joshua Greene, unpack both the psychological mechanisms and evolutionary roots of our moral judgments. The conversation expands to global challenges and asks: can our rational minds be strengthened to meet the demands of an interconnected world?

Key Discussion Points & Insights

1. The "Killing Babies" Dilemma: Personal Love vs. The Greater Good

• Setup of the Moral Dilemma (03:08)

  • A familiar scenario from MAS*H is introduced: you must decide whether to smother your own baby to save a group hiding from soldiers.
  • Joshua Greene: “If they hear your baby, they're gonna find you and the baby and everyone else, and they're gonna kill everybody. The only way you can stop this... is cover the baby's mouth. But if you do that, the baby's going to smother and die...” (02:49)

• Host Reactions (03:34–04:05)

  • Jad Abumrad: Initially rationalizes killing the baby for the greater good.
    • “I would kill the baby. The village will go on to have 100 babies. Your baby is just one.” (03:48)
  • Robert Krulwich: Emotionally rejects the idea due to personal attachment.
    • “My baby is my world. My baby is my universe.” (03:53)
  • Jad revisits his position now that he has his own child:
    • “Now this is not just like an abstract baby, but it's my baby. That does change everything, obviously... I don't really know. I frankly don't know.” (04:36–04:49)
    • He admits: “I can't kill my baby, but then I can't sacrifice the village. So I think I would just, like, close my eyes and wish I was somewhere else.” (06:05)

2. The Brain in Moral Judgment: Competing Systems

• Greene: Emotional Reflex vs. Calculated Reasoning (06:17)
  • “On the one hand, you have an intuitive emotional response... At the same time, a different system within your brain is saying... this is the only sensible thing to do, because if you do nothing, everyone will die.”
  • Greene explains that these “competing moral perspectives are really grounded in different parts of the brain.”

3. Local vs. Global Morality

• Analogous Dilemmas: Saving a Child Next to You vs. Donating to Distant Strangers (07:20–08:03)

  • Krulwich: “Suppose that you are walking alongside a lake and you see a girl drowning... but you're wearing a very expensive suit. Should you jump in the lake and save her?”
  • Most people say yes. But if asked to send $1,000 to save a girl overseas, most don't feel the same obligation.

• Evolutionary Explanation (08:28–08:53)

  • Greene: “A lot of our social emotional responses are geared towards life in the kind of environment in which our ancestors evolved... the idea of spending a minimal amount of money to save the life of some stranger on the other side of the world... is not something our emotions are prepared for.”

4. Can Rationality Scale to Global Problems?

• Abstract Challenges: Climate Change & Global Morality (09:14–09:59)
  • Krulwich: “What happens if the most important questions that we face as a species... involve thinking abstractly?”
  • Greene: “What we call common sense, is really hunter-gatherer common sense... If we're going to face these big problems... Then we have to learn to turn off parts of our brain that are getting in the way and turn on other parts that may seem like the wrong parts to be using.”

5. Are We Equipped for Abstract Thinking?

• Chocolate Cake and the Limits of Rationality (11:00–13:38)

  • Experiment by Baba Shiv: People asked to memorize a 2-digit or 7-digit number and then choose between cake or fruit.
    • Tired brains (7 digit-memorizers) pick cake; fresher ones, fruit.
  • Krulwich: “Your rational system—the hope of humankind... is very, very suggestible, weak... Oh man, it just wants sweet cake.”

• Greene’s Rebuttal (13:38–14:32)

  • “...If you told those people how their mind works... I think a lot more of them are [able to resist cake]... We can recognize the quirks and the flaws... and do something better that makes more sense.”

6. The Flynn Effect: Are We Getting Smarter? (14:36–16:52)

• Greene: “Over the course of the 20th century, IQ scores kept going up and up... By his [Flynn’s] estimates, a person of average intelligence in 1900 would register somewhere near the line for mental retardation by present standards...”
  • The implication: cultural evolution and societal complexity have improved our abstract reasoning skills, not our basic nature.
  • “Things like thinking about a market... have become part of our cognitive backdrop... Cultural evolution essentially has given us much higher IQs when it comes to thinking about a lot of things.” (16:27, 16:46)

7. Hope for the Future: Can We Exercise Our Rationality? (17:05–18:33)

• Greene: “It's like learning to play an instrument... we can learn to play our dorsolateral prefrontal cortices better.”
• Krulwich: “At the end of the day, you think the pressure of dealing with these big abstract problems will eventually change our minds?”
• Greene: “Well, I hope so... The problem is that as a species, we tend to learn from trial and error. The problem with issues like nuclear proliferation and global warming is that we only have one Earth... But I also think that there's reason for optimism.” (17:46–18:08)

Notable Quotes & Memorable Moments

• On Personal Love vs. Utility:
  • “My baby is my world. My baby is my universe.” – Robert Krulwich (03:53)
  • “But I don't think I could do that. I don't think any father could do that.” – Jad Abumrad (05:43)
• On Evolution and Morality:
  • “A lot of our social emotional responses are geared towards life in the kind of environment in which our ancestors evolved.” – Joshua Greene (08:28)
• On Human Progress:
  • “Cultural evolution essentially has given us much higher IQs when it comes to thinking about a lot of things.” – Joshua Greene (16:46)
• On Rationality and Hope:
  • “We can learn to play our dorsolateral prefrontal cortices better.” – Joshua Greene (17:34)
  • “It's worth a shot, to see if we can teach ourselves to live happily on a small planet.” – Joshua Greene (18:23)
• Humorous Both-Sides Wrap-up:
  • “We should wrap. We should kill this baby.” – Jad Abumrad, joking while ending the episode (19:08)

Important Timestamps

• 03:08 – The wartime baby-smothering moral dilemma explained
• 04:36–06:05 – Jad reflects on his answer now that he’s a parent
• 06:17 – Joshua Greene explains the competing brain systems in moral judgment
• 07:20 – The lake rescue analogy and distant charity dilemma
• 08:28 – Evolutionary psychology and emotional responses
• 11:00–13:38 – Baba Shiv’s experiment: Cake vs. fruit, rationality under cognitive load
• 14:36–16:52 – The Flynn Effect and growing abstract reasoning
• 17:05–18:33 – Can we ‘exercise’ our rationality to face global issues?
• 19:08 – Lighthearted conclusion and sign-off

Summary Takeaway

Radiolab's "Killing Babies, Saving the World" probes the fraught terrain of moral choice, from ancient instincts to the hopeful evolution of our brains. The episode deftly moves between relatable hypotheticals (would you smother your baby to save many?), psychology labs, and the sweep of human progress, ultimately asking: can our growing cognitive capacities meet the challenges of modern interconnected life?

Bottom Line:
Our morality is a tug of war between ancient emotional instincts and our unique rational minds. Greene and the hosts suggest optimism: brains, like muscles, can be trained for the complex decisions of a small, crowded world—if we dare to put in the work.