Podcast Summary: Armchair Expert with Dax Shepard

Episode: Steven Pinker Returns (on Common Knowledge)
Release Date: September 24, 2025
Host: Dax Shepard (with Lily Padman)
Guest: Steven Pinker (Harvard Professor, Cognitive Psychologist, Author)
Topic: Common Knowledge and the Mysteries of Money, Power, and Everyday Life

Overview

This episode features the return of renowned cognitive psychologist and author Steven Pinker, who joins Dax Shepard and Lily Padman to discuss his latest book, When Everyone Knows That Everyone Knows: Common Knowledge and the Mysteries of Money, Power, and Everyday Life. The episode unpacks the idea of "common knowledge"—what it is, how it differs from private knowledge, and why it underpins so much of human cooperation, culture, economics, and political life. Pinker and the hosts also weave in broader discussions about optimism, progress, societal coordination, language, and the challenges of truth in information-dense modern cultures.

Key Discussion Points & Insights

1. Steven Pinker’s Return & The Importance of Optimism

• Dax and Lily are excited to host Pinker in person, noting his reputation as an optimistic thinker who offers a fact-based, hopeful perspective on human progress.
• Pinker clarifies his outlook is not mere optimism, but attentiveness to data that’s often overlooked by headline-driven media.
• He emphasizes:

  “It's not really optimism. It's really more just attention to facts, to data that you don't get from the news..." (09:37)

2. Life in California & Silicon Valley's Shifting Politics

• Pinker reflects on a year in Berkeley, being exposed to “granola culture” and the rationality community.
• He contrasts the “can-do spirit” of Silicon Valley with the more pessimistic intellectual tone in Boston.
• He discusses the recent political shifts among tech elites, noting a movement from centrist libertarianism to reactionary or even monarchist ideas as a backlash to “wokeness” and anti-tech sentiment.
• Dax adds that both the political left and right have increasingly developed an anti-tech “techlash.”

  “If the left likes it, then it must be awful.” (06:33)

3. Progress, Crisis, and How We Perceive Risk

• Pinker reviews misleading perceptions about progress due to the media’s coverage of sudden, often negative, events.
• He references the overall trends of reduced war deaths, increased life expectancy, and improvements in global poverty and democracy, reminding that setbacks are typically “blips” rather than true reversals.
• He introduces the "availability bias"—our tendency to overestimate risks based on the most recent or vivid events.
• Memorable quote:

  "You don't see a headline about a region of the world that isn't having a war. … But if you look at the trends, it shows that we really are better off than people before us." (10:14–11:03)

4. Defining “Common Knowledge” (Technical vs. Casual Meaning)

• Pinker distinguishes the technical, recursive definition from informal usage.

  “Common knowledge in the technical sense is, I know something, you know it. I know that you know it. You know that I know it. … ad infinitum. So that's common knowledge.” (15:55)

• Example from Friends: “They don't know we know they know we know.” (16:43)

Private vs. Common Knowledge

• Private: “Everyone knows, but no one knows that anyone else knows.”
• Common: "Everyone knows and you know that everyone knows..."

5. Implications of Common Knowledge

• Common knowledge enables social conventions, coordination (rendezvous, protests), and collective action.
• Pinker’s examples:
  • The Emperor’s New Clothes: The boy’s outburst makes the emperor’s nudity common knowledge, changing social dynamics instantly. (20:09–21:18)
  • Money: The value of money is predicated on common knowledge—everyone accepts currency because everyone else does. (22:01)
  • Public protest: Why autocrats fear demonstrations—these create visible, undeniable collective sentiment. (22:01–25:31)
  • Rendezvous Problem: Language and rituals are tools for generating common knowledge quickly and unambiguously (wedding ceremonies, traffic rules, etc.).

6. Euphemism, Indirect Speech, and Social Relationships

• Pinker explores why humans use indirect speech, euphemisms, and ambiguous language in sensitive social contexts (e.g., “Netflix and Chill”).
• The purpose: Maintain plausible deniability, prevent creating unwanted common knowledge, and protect relationships from irrevocable changes.

  “What I thought was fascinating was ... they can maintain a plutonic relationship in the wake of 'Netflix and Chill', but 'I'd like to come upstairs and have sex with you' ... we cannot participate in this illusion ... anymore.” (37:14)

7. Focal Points & Coordination Without Explicit Agreement

• Focal points: How people coordinate when communication isn’t possible (e.g., the clock at Grand Central).
• Used in bargaining, international relations, and even animal behavior (e.g., coral spawning on a fixed night after a full moon).

  “So a focal point or common salience is when you don't have common knowledge ... Not because necessarily it was convenient … but if anything is going to pop into someone's mind, that would be just because it sticks out.” (38:44)

8. Common Knowledge in Economics & Marketing

• Stock Market: Keynes’ “beauty contest” analogy explains speculative bubbles, meme stocks, and the importance of anticipating what others will do.

  "You're picking the stock that you think other people are going to pick..." (44:27)

• Super Bowl Ads: Products that require mass adoption (credit cards, tech platforms) use widely viewed events to generate common knowledge, fostering network effects.

  "If you advertise in public, where other people know what a Nike wearer is like ... then they're likelier to identify with a product." (50:02)

9. Common Knowledge and Social Standing in Philanthropy

• The paradox of visible vs. anonymous charity, drawing on Maimonides’ ladder of righteousness—double-blind giving is “most righteous,” but public giving encourages others (effective altruism).

  "They agree that a common knowledge gift is less righteous than a double blind gift. That is the person is more generous is more likely to donate in the future." (57:00)

• Curb Your Enthusiasm parody highlighted this social paradox. (57:02)

10. Cooperation, Mutualism & Social Coordination

• Evolutionary biologists’ views on cooperation: Not all helping is altruistic; mutualism is about mutual benefit, not self-sacrifice.
• Coordination problems exist for all animals; humans use knowledge, animals evolve simple focal points (e.g., moonlight for spawning coral). (63:13–64:41)

11. Current Events: COVID, Academia, and Political Polarization

• Pinker critiques the failures in COVID response: overstated certainty, lack of transparent cost-benefit analysis, and suppression of dissent.

  "It's not immoral to suggest those things in a state of knowledge and say we don't know. ... But at this point we're hedging our bets." (69:45)

• On academia’s left-leaning reputation: It’s problematic for public trust and for intellectual diversity. Suppressing alternative viewpoints can hinder discovery and truth-seeking.

  "You've got many departments where it's 100% left and you know the left isn't right about everything." (75:40)

12. AI Fears: Should We Be Terrified?

• Pinker downplays existential fears about artificial intelligence, attributing them to anthropomorphizing machines rather than technical realities.

  “In the case of something that is designed by humans ... there's no automatic reason to think that they should want to maximize their power, maximize their well being.” (80:34)

13. Moralism and Mob Behavior

• Much violence is driven by moral convictions, not just self-interest; common knowledge of wrongdoing enables coalitions and mobbing.

  "As I put it, the world has far too much morality." (83:56)

Memorable Quotes & Moments

• On the News and Progress:

  “Anything that happens suddenly is almost certain to be bad ... Good things tend to build up a few percentage points at a time, and they can compound and transform the world.” (10:10–10:14)

• On Euphemism and Indirect Communication:

  "If she [knows the code] turns it down, it’s less painful ... it gives you deniability of common knowledge." (35:04–36:30)

• On Super Bowl Ads as Network Effect Triggers:

  "For products that depend on network effects ... companies are willing to pay more per viewer and more likely to advertise in the super bowl." (50:02–51:14)

• On Academic Freedom:

  "No one's infallible. Kind of expose ourselves to a universe of ideas and find out which ones are good." (79:37)

• On Moralism:

  “The world has far too much morality.” (83:56)

Noteworthy Timestamps

| Timestamp | Topic / Quote | |---|---| | 09:37 | Pinker on optimism: “It's not really optimism. It's really more just attention to facts, to data that you don't get from the news...” | | 16:05 | Technical definition of common knowledge | | 20:09 | Emperor’s New Clothes explained as a common knowledge moment | | 35:04 | The function of “Netflix & Chill” and indirect speech | | 38:44 | Focal points and the Grand Central Station analogy | | 44:27 | Keynes’ beauty contest and the stock market | | 50:02 | Super Bowl ads and generating common knowledge for networked products | | 57:00 | Philanthropy: the common knowledge ladder of righteousness | | 69:45 | COVID-19: importance of honest uncertainty and cost-benefit analysis | | 75:40 | Problems of academia’s political monoculture | | 80:34 | AI will not crush humanity—anthropomorphizing the issue | | 83:56 | “The world has far too much morality.” (on moral aggression and witch hunts) |

Tone and Language

Pinker maintains a clear, witty, and layered intellectual style, with Dax and Lily unpacking concepts in an accessible and often humorous way. The conversation is lively, thoughtful, and peppered with pop culture examples that ground complex ideas (e.g., Friends, Princess Bride, Curb Your Enthusiasm). Dax frequently turns to analogies and personal confessions to clarify psychological insights, while Pinker offers precise technical language and research-backed evidence to support his explanations.

Final Thoughts

Pinker’s newest book and this conversation reveal the hidden scaffolding beneath human society—how collective rituals, conventions, and even fictions all rest on invisible but crucial “common knowledge.” The episode connects philosophy, psychology, history, economics, and daily life, making the abstract feel urgent and practical. Listeners come away challenged to rethink how we coordinate, cooperate, persuade, and even disagree, with Pinker’s characteristic blend of data, clarity, and optimism offering a refreshing antidote to cynicism.

If you found Steven Pinker’s arguments compelling, his new book, "When Everyone Knows That Everyone Knows," digs deeper into all these paradoxes, from wedding rings to war and money to memes.