Carl Sagan vs. Immanuel Velikovsky

Was Carl Sagan on a crusade to destroy Immanuel Velikovsky? Some have speculated that their conflict was rooted in personal or even religious differences. But the truth is far more revealing—and relevant today. In this post, we explore what drove Sagan to engage so forcefully with Velikovsky’s controversial theories about Venus, myth, and ancient catastrophe. We examine Sagan’s commitment to scientific literacy, the 1974 AAAS conference that sparked debate, and the deeper question behind it all: How do we separate truth from persuasive fiction?

Immanuel Velikovsky (1895–1979)

• A Russian-born Jewish scholar, trained in medicine and psychoanalysis, not astronomy or physics.

• Emigrated to the U.S. during WWII.

• Published Worlds in Collision (1950), arguing that:

  • Venus was ejected from Jupiter as a comet.

  • It passed close to Earth within human memory.

  • Ancient catastrophes (plagues, floods, etc.) were due to planetary encounters.

  • Myth, scripture, and folklore preserve real cosmic events.

His theories were non-mainstream and widely rejected by astronomers and physicists.

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Carl Sagan (1934–1996)

• A renowned American astronomer, astrophysicist, and science communicator.

• Of Jewish heritage (born to Russian-Jewish immigrants), but personally agnostic/atheist.

• Passionate advocate for the scientific method, skepticism, and public education.

• Known for Cosmos, Contact, The Demon-Haunted World, and Broca’s Brain.

• Opposed pseudoscience not out of hostility, but as a defender of rational inquiry and empirical truth.

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Why Did Sagan Oppose Velikovsky So Strongly?

1. Scientific Integrity

• Velikovsky’s claims violated core laws of physics (gravity, conservation of energy, planetary motion).

• He misused myth and selective interpretation to support cosmic claims.

• Sagan believed that allowing such ideas to go unchallenged would damage public understanding of science.

“The truth may be puzzling, it may take some work to grapple with. It may be counterintuitive. But it is always better than lies.” — Carl Sagan

2. The Crisis of Public Credibility

• Worlds in Collision was a bestseller.

• Velikovsky gained mass public attention, but little to no support among working scientists.

• Sagan feared this reflected a dangerous gap between public enthusiasm and scientific literacy.

He saw Velikovsky’s popularity as a symptom of a society more moved by mystery than method.

3. AAAS 1974 Symposium

• Sagan did not campaign to “cancel” Velikovsky.

• In fact, Sagan supported Velikovsky’s right to speak, even at the AAAS.

• However, he insisted that science must respond with rigorous critique, which is what he attempted with his paper and later in Broca’s Brain.

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Was Religion a Factor?

Immanuel Velikovsky:

• Yes, Jewish by heritage and culturally connected to Jewish texts and ideas.

• His interpretations of ancient scriptures (especially the Hebrew Bible) gave literal cosmological weight to traditional narratives.

• His catastrophist cosmology had a kind of quasi-religious reverence for ancient myth as literal history.

Carl Sagan:

• Also Jewish by birth, but secular in practice.

• Profoundly influenced by Enlightenment values, the skeptical tradition, and thinkers like Spinoza and Einstein.

• Sagan often defended religious sentiment, but rejected dogma and demanded evidence.

“Science is not only compatible with spirituality; it is a profound source of spirituality.” — The Demon-Haunted World

So, Sagan’s opposition was not religious, nor was it personal or ethnic. It was philosophical and epistemological: What does it mean to know something? How do we distinguish truth from compelling fiction?

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Velikovsky as a Case Study in Pseudoscience

Sagan believed Velikovsky’s work demonstrated the classic hallmarks of pseudoscience:

• Lack of predictive power

• Immunity to falsification

• Appeal to authority via myth

• No empirical mechanism

• Selective data use

• Charismatic persuasion instead of peer review

That made it worth confronting—not to “destroy” a man, but to defend the integrity of science itself.

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Final Thoughts

Carl Sagan did not hate Velikovsky. In fact, he admired his creativity and courage, and thought it was appropriate for Velikovsky’s ideas to be heard—so long as they were fairly examined and scientifically tested.

He saw Velikovsky’s rise as a cultural warning: that without scientific education, the public could be misled by ideas that felt good but were demonstrably false. And in that sense, Velikovsky’s popularity became for Sagan a kind of cautionary tale—not about religion, but about the fragility of truth in a world full of noise.